News media have reported that the Government is withholding the publication of a report that found the number of UK workers unemployed as a consequence of immigration is lower than has been previously claimed.
BBC's Newsnight programme broke the story.
According to BBC News, Theresa May has previously used research from a 2012 Migration Advisory Committee (MAC) study which said "for every additional 100 immigrants… 23 British workers would not be employed."
The new report, written by civil servants, has concluded that the figure is actually much lower.
According to BBC News, the report was ready last year but was not published as it was considered "potentially incendiary".
However, Downing Street sources told the BBC the report had not yet been completed and was not ready to be released.
In addition, BBC News reported that Home Office officials said the report, in parts, reflects an "institutional bias" in favour of migration among officials at the Treasury, Foreign Office and business department.
BBC News says, however, that the report had been checked by external academics and agreed across all Government departments with a hand in migration, including the Home Office.
According to the Guardian, internal Government emails seen by BBC Newsnight suggest that the cross-governmental report was commissioned because the original MAC research was not considered sufficiently "robust" by either the Treasury or the business department.
In a press statement, Labour's David Hanson MP, shadow immigration minister, said the Government needs to publish the report straight away.
"The British people should have information made available to them so they can make a judgement about the impact of immigration on jobs. This should be done on the basis of fact not more empty rhetoric or spin from the Government," Hanson said.
According to BBC News, Downing Street sources insisted that the report would be published "in due course".