Facebook is embroiled in a row with a group of British activists who say it is "censoring" material that might offend the Turkish government.
Three activists – 27-year-old student Rosa Gilbert, pro-Kurdish rights campaigner Mark Campbell, and British Kurd Ari Murad – all say Facebook unfairly removed posts that they insist did not breach community standards.
Posts they say were deleted include images of graffiti and protest signs accusing Turkey of oppressing the Kurdish minority in the country.
The social media giant confirmed a number of posts had been deleted in accordance with its community standards that ban references to terrorist organisations, in this instance the Turkey-based Kurdish militia group PKK.
It also admitted to removing some posts in error that have since been reinstated, though declined to give detail on what these were.
But the tension between Facebook's users and its moderation policy highlights the tightrope it faces in balancing freedom of expression with moderating content deemed illegal in other countries.
It also shines a spotlight on Turkey's laws and how these apply internationally. In Turkey, where it is illegal to insult the president, the government has faced heavy criticism for blocking social media sites in times of political unrest.
Facebook's own internal data, published biannually, shows a significant increase in requests from Turkish authorities last year asking it to make content restrictions – the same year Turkey temporarily banned Twitter and YouTube after users spread allegations of government corruption.
Turkey is among a number of countries, including the UK, the USA, and India, that makes thousands of such requests each year, but it appears to have a high level of success in persuading Facebook to translate those requests into action.
Between January and June 2015 Facebook made 4,496 content restrictions in response to requests from Turkey. The number appears high when compared with the number made in response to the UK, which managed just eight content restrictions over the same period.
Many of the Facebook restrictions, as outlined below, related to "criminal cases" in regard to the Turkish law 5651, which enables the country to block terrorism-related content as well as content featuring crime and drugs.
The activists showed BuzzFeed News screenshots of posts that had been removed, and accused Facebook of enacting "political censorship" on Turkey's behalf.
They claimed the volume of posts being removed is increasing, something Facebook denied, and that the net has been cast widely to avoid offending Turkey.
Rosa Gilbert, who helps run a hard-left Facebook page called World Riots that describes itself as "anti-capitalism, anti-fascism, anti-racism", claims she was suspended from Facebook after one of her posts, above, was removed for "violating" community standards.
Another post, which she admits may have fallen foul of Facebook's anti-terrorism rules, depicted Turkey's president, Recep Tayyip Erdogan, as an ISIS executioner. The content she posts is evidently political.
But she refuses to believe that the mural above fell foul of the rules and labels its suspension an act of deliberate "censorship".
The graffiti references Kobane, a town in Syria under the rule of the YPG, a Kurdish militia group. The town has held out against ISIS with the help of USA air support.
The militia group has close links with a banned political organisation in Turkey called PKK, which is internationally recognised as a terrorist group.
The YPG, which is supported by the USA, is not. But it is outlawed by Turkey.
"To me it seems the only dangerous political message from that is the notion that this nation is resisting," said Gilbert, pointing out that Kobane and the graffiti has become a symbol of hope and resistance against ISIS.
She fears Facebook deleted in a complicit act with Turkey to silence the voice of political movements that threaten the establishment.
In particular, she argues it is the Kurdish voice that is most silenced, because the largest minority group in Turkey has clashed repeatedly with the government for greater autonomy, sometimes with bloody and violent consequences on both sides.
"Obviously my access to Facebook is not the most pressing issue when it comes to the repression of the 'Kurdish struggle' and the left in Turkey, but it is troubling," Gilbert said.
She pointed BuzzFeed News to a leaked document, first published in 2012 by the US site Gawker, that provides a snapshot into Facebook's moderation policy.
The international compliance section of the document, which Facebook said was now updated and did not reflect changes introduced, shows there are specific rules related to the country.
The rules instruct moderators to moderate criticism of Mustafa Kemal Atatürk, the first president of Turkey, as well depictions of the burning of Turkish flags and references to the PKK. The only other offence under international compliance listed in this document is holocaust denial.
"If you're going to have these political censorships you have to be as explicit as about them as the rule [that bans] nude pictures," Gilbert said.
"If it was an equal application of condemnation of violence that would be one thing, but they are clearly led by Turkey."
Facebook defended its removal of any references to the PKK because it is an "internationally recognised terrorist organisation, and terrorist content is not permitted on Facebook".
It also did not deny the document was genuine. But it did say it was now outdated and that Turkey was not the only country that it had specific international rules for.
It denied it had any "moderation agreement" with the government or to specify how it was now out of date. But said it dealt with millions of reports globally, was not "ramping up" any removal of posts and could not speculate on why there had been an increase in requests from Turkey.
The document does appear to prove, however, that Facebook has country-specific compliance guidelines imposed internationally. But what Gilbert, and other activists who came forward argue against is Turkey's right for those rules to be implemented in the UK and infringing on what they see as their right to free speech.
In its publicly available community standards, Facebook outlines that it does, in response to government requests, a times "remove content that violates local laws but does not violate our Community Standards" – but only after careful legal review, and only in the relevant country or territory.
Ari Murad, a Kurdish activist living in London, claims he set up fake Facebook profiles and posted pro–al-Qaeda content online to see how quickly Facebook reacted – and to test its anti-terrorism policy.
He claims the content is still online and he showed BuzzFeed examples of posts featuring explicit images of murdered bodies, along with racist and violent comments praising and encouraging the use of chemical weapons against Kurdish people.
"Of course this isn't censorship on terrorism," he said. "This is Turkey's censorship policy implemented on an international level."
"It is the Turkish state having authority on the world [and] a massive attack on free press, something Turkey knows very well."
Another political activist, who runs the pro-Kurdish rights campaign group Stop the War on Kurds, says he was banned from Facebook for 30 days for posting pictures of a peaceful demonstration that took place in Westminster, London, in March.
Mark Campbell, who is organising a demonstration against Facebook in May, showed BuzzFeed News examples of where the group's logos were also removed, even though they do not depict violence and do not appear immediately to fall foul of Facebook's content rules.
Facebook did not comment on specific posts but said that in times of conflict users tended to report more content, resulting in an increase in posts being checked and moderated.
It also reiterated that its community standards prohibit hate speech, terrorism, and specific threats of violence and said its global team prioritised terrorism-related reports, in particular from violent and unstable regions.
"Therefore, pages supporting the PKK have been removed," a spokesperson said. "However, some pages were taken down in error, and they have now been restored."