According to a confidential National Crime Agency (NCA) report, "specific information" relating to the sexual abuse of children and a situation in which female migrants are selling sex in return for their entry to the UK was passed to the Home Office this summer (2016).
The NCA report, leaked to The Sunday Times, includes details which have been sent to intelligence officials in France.
"Where the NCA has received specific information about the abuse of children, we have shared the information as soon as possible with the French authorities."
"French authorities have established investigations as a result, but have not yet been able to take legal action."
The NCA report also includes details about female migrants selling sex to secure their entry into the UK and information taken from a previous UNICEF report, which warns that children work in "near slave-like conditions" and "sexual abuse appears to have been commonplace."
Reports in British media which cite the leaked NCA report, insist that the full extent of the problem, which has been circulated to intelligence agencies, the Ministry of Defense and the police, is not yet known and the scale of the sexual abuse remains unclear.
"There is an intelligence gap on the sexual exploitation of migrants including minors, particularly in the context of a reported increase in the numbers of unaccompanied minors on the migration routes. We are particularly looking for intelligence linking sexual exploitation to immigration OCGs (Organized Criminal Groups)."
The leaked report was also sent to Prime Minister Theresa May when she was serving as the UK government's Home Secretary. Mrs. May is currently in New York for a United Nations leaders' summit on refugees and migrants.