Lawyers supporting Afghan refugees evacuated to the UK last summer say some are on the verge of accidentally becoming illegal immigrants because they have not received updated papers.
In an appeal to ministers, solicitors said that increasing numbers of Afghans are anxious about their visas.
They say they have heard nothing about their status, days before temporary visas will expire.
The Home Office has hit back saying the warning is needless scaremongering.
When the UK evacuated some 15,000 Afghans to the UK last August, the Home Office issued six-month visas to the refugees, with a view to giving them a permanent right to settle later on.
That commitment still stands as part of the resettlement plan but the Law Society, which represents solicitors, said firms across the UK are now receiving calls for help from people whose temporary legal status expires in the coming week.
In each case, Afghans are saying they have not received any updated papers or they are struggling to get answers from officials.
It is not clear how many Afghans are affected.
Despite two recent parliamentary questions, ministers have not revealed how many of the evacuees have been granted their final permanent status – but they have said they “aim” to conclude the process before current visas expire.
However, under the law, immigrants must be able to show on request a valid visa to rent a home, work or claim benefits, open a bank account and use all of the NHS.
If they cannot produce a valid visa whenever it is requested, they can be denied services.
One Afghan, who was evacuated after working for the UK and its allies for almost 20 years, told BBC News that he was increasingly concerned about his status.
He had found himself a new home and begun applying for jobs – but employers had repeatedly refused to take him on amid uncertainty about his long-term right to be in the UK.
“Since the end of September, I haven’t heard anything from the Home Office,” he said.
“My visa will expire on 26 February. I have tried to contact them – sending emails to the Afghan resettlement scheme people.
“But I haven’t received any response. It’s almost six months.