A UK Border Agency IT system crashed on Thursday, leaving hundreds of foreign nationals unable to get their biometric visas and residence permits.
It is not yet clear which system was affected by the outage, but the BBC reported on Thursday that some people at the Croydon Enquiry Office in south London broke down in tears when they were turned away from their appointments.
"We did have a IT outage yesterday but our system is now back up and running," the Home Office, which is responsible for the UK Border Agency (UKBA), said in a statement. "There will be a small backlog of appointments to clear. Anyone who needs an urgent appointment will get one."
Last year, the National Audit Office reported that poor IT systems were hampering the border agency's ability to efficiently process migrant applications, among other paperwork. It called out supplier Fujitsu in particular, saying it had "underestimated the complexity" of designing a key system.
According to the BBC, officials told the foreign nationals on Thursday that they could rebook their appointments online or via postal application.
Meanwhile, The Guardian reported that this would lead to significant delays, and that some applicants had been offered replacement appointments "at the other side of the country".
Both reports suggested that the computer system had been crashing repeatedly in recent months, although not so severely as to cause an outage of the likes seen on Thursday.