The UK Home Office has revealed that 99 suspected war criminals made immigration applications in the UK last year.
Under a Freedom of Information Act request from the BBC, the Home Office said suspects came from countries including Afghanistan, Iran, Iraq, Libya, Rwanda, Serbia and Sri Lanka.
The figures show that in the 15 months from January 2012, the Home Office researched nearly 800 cases where individuals were suspected of war crimes and crimes against humanity.
Three of the suspects were deported last year, 20 were refused asylum and 46 were refused Birtish citizenship, although it is likely that they remained in the UK.
Human rights organisations called for prosecution of suspects.
James Smith, from the charity Aegis that works to prevent crimes against humanity, said, prosecution could take place in the UK.
"There's a cost and it is difficult to investigate crimes which took place in another country a long time ago. But if we don't pursue those prosecutions, the UK could become known as a retirement home for war criminals," he said.