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.