Andrew Tingley, an immigration lawyer at Kingsley Napley, said it was "beyond farcical" that new rules requiring foreign nationals from outside the EU to have a biometric residents permit had left the IT system unable to cope.
The system that was introduced was not fit for purpose. It was close to collapse a few weeks ago. It has now collapsed. It's an absolute mess.
Mr Tingley also warned of the impact on the UK's economy.
You have senior global managers and directors of companies saying, 'enough is enough'. Employers are saying they can't access a reasonable immigration system and they're considering moving abroad.
They've come to the point now where they're seriously considering not investing or working in the UK because they can't access any reasonably competent system.
More top news
Germany's spy agency is facing one if its most embarrassing leaks after thieves broke into the building and stole the taps.
A 14-year-old boy was tied up and threatened with a machete by burglars when he was home alone.
James McClellan, 53, is suing the firm claiming he was branded an 'old buffer' and forced out of his account manager job.