Parents are sharing letters and text messages from their children's schools requesting information on the child's country of birth, in some cases specifying that they only need to know if the child was "not born in the UK".
The data is being collected as part of the National School Census, which took place across the UK on 6 October and will this year, for the first time, collect data on where in the world a child was born.
Tim Colbourne, who was deputy chief of staff for former Liberal Democrat leader Nick Clegg, tweeted a letter and text message issued by Dulwich Hamlet Junior School in south London that specified that it only wanted information on children's nationality and country of birth if they were born outside of the UK.
"You do not need to respond if your child was born in the UK and is a British National," the letter said, while the text message specified that the information was only required "if your child is not of British Nationality or was not born in the UK".
Dulwich Hamlet Junior School declined to comment when contacted by BuzzFeed News.
In September, Schools Week reported that Garth Hill College in Bracknell had asked only parents of non-British children to urgently declare their nationality and country of birth, while St Richard’s Church of England First School in Evesham requested pupils' passport numbers.
After Colbourne's tweet containing the text message was retweeted more than 1,000 times, several other parents shared communications from their children's schools requesting similar information.
While parents do have the right to refuse to disclose their child's nationality and country of birth, some schools did not make this clear in their communications.
Letters shared by parents stated that the school was "required" to collect the information for the school census, but did not clarify that parents were not required to provide it.
A spokesperson for the Department for Education told BuzzFeed News there is no requirement for parents to provide a birth certificate or passport and that schools had been issued with guidance saying parents could refuse disclose the information.
“This data will help ensure our children receive the best possible education," the spokesperson said. "It will be used to help us better understand how children with, for example, English as an additional language perform in terms of their broader education, and to assess and monitor the scale and impact immigration may be having on the schools sector.”
Kojo Kyerewaa, a spokesperson for campaign group Against Borders for Children, which seeks to boycott the collection of data on children's nationality, told BuzzFeed News that in the last week the group had been "inundated" with emails and tweets from parents who had received communications from their children's schools.
Many had not been informed that they had the right to withhold the information, Kyerewaa said, adding: "Parents have been worried."
The decision to begin collecting country of birth and nationality data was made by the DfE in May, but the increase in anti-immigrant sentiment since Britain voted to leave the European Union in June has left parents increasingly concerned about how the information might be used.
Kyerewaa said home secretary Amber Rudd's announcement at this week's Conservative party conference that businesses could be forced to publish data on how many foreign workers they employ exacerbated these fears.
"We are very concerned that this policy [making businesses disclose data on their foreign workers] can eventually lead to a future policy where they would want to do that for schools as well," he said.
Catherine Aman, whose daughter was born in New York, told BuzzFeed News she provided the data to the school in Cambridge her daughter has attended for the past six years, but she found the request unusual. The school informed her of her right to decline to respond.
Aman is American and has the indefinite right to remain in the UK so did not mind providing the information, because "we’re kind of in the system anyway", but said that in the context of an "increasing suspicion of foreigners" it did feel "a little bit sinister".
She said she did not blame her daughter's school, which is very liberal and attended by a large number of non-British children, but was concerned about the government's increased interest in where children are born.
"I wonder if is this the tip of the iceberg, or the beginning of a slippery slope that will end up with us having to pay for her education?" she said. "It feels like a chill in the wind."