More than 200 people responsible for war crimes and other human rights abuses overseas could be living in Britain, the BBC has learned.
File on 4 has discovered that many of the alleged perpetrators are known to the government's UK Border Agency.
The agency recommended rejecting more than 300 asylum or immigration claims in five years of people suspected of crimes against humanity.
Only a handful of cases have been referred to the police.
Figures seen by File on 4 show the UK Border Agency's war crimes team recommended rejection of 330 asylum and immigration claims in five years, on the grounds it suspected the applicants of war crimes or crimes against humanity.

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But less than half of those were actually excluded.
The figures do not include people who entered the country illegally or were not spotted by the authorities.
One estimate suggests that this could be another 100 people
Police plea
Only 22 cases of people alleged to have been either war criminals or human rights abusers have been referred to the police in the last five years.
And there have been claims some investigations failed because of a lack of resources or expertise.
The government's reviewer of anti-terrorism legislation, Lord Carlisle, said that needed to be rectified.
"I would hope that the new Metropolitan Police Commissioner would think it right to set up an additional unit, just as one of his predecessors set up the war crimes unit, to investigate international criminal matters of this kind, " he told the BBC.
"There is a suspicion around the world that the United Kingdom gives safe haven to people who have committed genocide and indeed torture.
"Some of them are suspected of the most appalling crimes, involving murder on a large scale," he added.
The Home Office said that the government was committed to dealing with human rights abusers.