Albanian criminals who pretended to be Kosovan refugees have been allowed to stay in the UK after a Supreme Court judgement revealed a “loophole in the law”.

The migrants’ court victory is expected to cost the taxpayer £1 million and thousands more could now be allowed to stay, even if they have committed serious crimes.

Tens of thousands of Kosovans migrated to the UK in the 1990s during the conflict in the Balkans, but thousands of Albanians also came illegally, pretending to be refugees to gain residence and even UK citizenship.

Dinjan Hysaj, 40, and Agron Bakijasi, 44, were part of that wave, being allowed to stay in 1999, The Telegraph reports.

However, Mr. Hysaj was exposed as having lied when he was jailed for five years in 2011 after glassing a man in a pub in Hemel Hempstead, Hertfordshire.

Mr. Bakijasi was exposed in 2007 when his partner returned to Albania. However, he reapplied using false details and was awarded British citizenship.

When the Home Office applied to have the crooks deported, their publicly-funded legal representatives argued that their lies were not enough to have them removed from the UK and it was not clear it could be a consequence when they applied.

The Supreme Court judges last week ruled that because the men had not stolen anyone’s identity but instead made up a fictional character, “neither appellant pretended to be someone he was not”.

The judges add: “It also has a number of illogical and unsatisfactory consequences. Thus it is not clear when the use of a false identity to obtain citizenship by one person will lead to the nullification of the grant of citizenship to those making a derivative claim.”

Andrew Bridgen, the Conservative MP, said this judgement exposed a loophole that needed new British legislation to ensure criminals could not abuse the British legal system.

“We need to tighten up the law so people who make up identities and lie to get British citizenship can be stripped of it and be deported. These are not the sorts of people we want to have in our country.

“This legal loophole that needs to be closed as soon as possible. We need to look at legislation to do so, especially as we are now leaving the European Union and we are supposed to be taking control of money, our laws and our borders.”