David Cameron has been overheard telling the Queen that Nigeria and Afghanistan are "two of the most corrupt countries in the world".
David Cameron told the Queen on Tuesday that there are some “fantastically corrupt” leaders attending an anti-corruption summit in London this week.
The summit, which starts on Thursday, plans to step up global action to expose corruption in all walks of life.
The prime minister was speaking to the Queen at an event at Buckingham Palace to mark her 90th birthday and was caught on camera by ITV. The event was attended by representatives from both houses of parliament.
"We had a very successful cabinet meeting this morning, talking about our anti-corruption summit," Cameron said to the Queen. "We have got the Nigerians – actually we have got some leaders of some fantastically corrupt countries coming to Britain."
Cameron added: "Nigeria and Afghanistan – possibly two of the most corrupt countries in the world."
While the Queen did not respond to Cameron's remarks, the Archbishop of Canterbury, Justin Welby, said: "But this particular president is actually not corrupt."
This is the second time in three years that Cameron has been overheard on camera by journalists. Following the Scottish referendum, the prime minister was caught telling the former New York mayor Michael Bloomberg that the Queen "purred down the line" when he told her that Scotland had voted to stay in the union.
At a regular briefing for journalists, the PM's spokesman said: "Both President Buhari of Nigeria and President Ghani of Afghanistan have acknowledged the scale of the corruption challenge they face in their countries.
"Both leaders have been invited to the summit because they are driving the fight against corruption in their countries. The UK stands shoulder to shoulder with them as they do so."
He pointed to a collection of essays to be published on the day of the summit in which Ghani acknowledges that Afghanistan is "one of the most corrupt countries on earth" and Buhari writes that corruption became a "way of life" in his country.
The spokesman ducked questions on whether Cameron had apologised to the Queen and whether he regretted the remarks being caught on camera.
While Afghanistan features second from the bottom of Transparency International's 2015 corruption perception index, Nigeria comes in at 136 (out of 167 countries).