In furious exchanges with Jeremy Corbyn at Prime Minister’s Question’s, Mrs May said she would not take lessons from a leader who “allows anti-Semitism to run rife in his party”.
But there was confusion as the government scrambled to respond to the spiralling crisis, with MP Chuka Umunna representing an elderly man denied vital cancer care because he couldn’t prove his nationality denying Mrs May’s claim that the case had been resolved.
Mr Umunna said Albert Thompson, who has lived in the UK for 44 years, had not been told he would get the radiotherapy he needs, and called on the Prime Minister to correct the record.
Earlier, at Prime Minister’s Questions, Mrs May had told MPs: “These people are British. They are part of us. I want to be absolutely clear that we have no intention of asking anyone to leave who has the right to remain here.
“For those who have mistakenly received letters challenging them, I want to apologise to them and I want to say sorry to anyone who has been caused confusion and anxiety by this.”
There was a furious row over who is to blame for the destruction of thousands of historic landing cards of Commonwealth citizens, amid claims that the documents could have helped confirm their immigration status.
Mr Corbyn challenged the Prime Minister to take responsibility for the decision, telling MPs: “This is a shameful episode and the responsibility for it lies firmly at the Prime Minister’s door.
“Her pandering to bogus immigration targets led to a hostile environment for people contributing to our country.”
But Mrs May said the destruction had taken place in 2009 under the former Labour government – even though the Home Office had previously said it was carried out in 2010, the year the Conservative-led coalition took office.
Her comments prompted shouts of “apologise” across the Commons chamber from Conservative MPs.
A Downing Street spokesman later said the UK Border Agency approved a business case in June 2009 to dispose of paper records, including the landing slips, and the process of destroying them began in December that year.
The operational decision to destroy the slips themselves was taken in October 2010, after the coalition came to power. Mrs May was not involved in the decision, which was taken at official level, said the spokesman.
A Labour Party spokesman later claimed the government’s position was “shifting by the hour”.
He said: “In the confusion, one thing is already clear: The change in the law in 2014 that meant members of the Windrush generation faced deportation and the loss of their rights, including to healthcare, was made in full view of the fact that the vital information had been destroyed.”
“The Home Secretary at the time must be held to account for the disastrous impact her ‘hostile environment’ policies have had on the lives of British citizens.”
The exchanges came as it emerged 49 people had on Tuesday contacted a new Home Office hotline set up to help Commonwealth citizens whose immigration status has been challenged.
The problems affected those arrived in the years up to 1973 - often as schoolchildren - who automatically received the right to live in the UK but who never acquired documents such as a passport, which could prove their status.
Shadow home secretary Diane Abbott said Home Secretary Amber Rudd should take responsibility for what had happened. “The way Amber Rudd is attempting to avoid responsibility is very concerning. I think she needs to consider her position,” she told the BBC’s Today programme.
Jamaican prime minister Andrew Holness, who is in London for a Commonwealth summit, called for compensation for those affected.
“My view is that if there is an acceptance that a wrong was done then there should be a process of restoration,” he told ITV’s Good Morning Britain. And I’m certain that the very strong and robust civil society and democracy that you have will come up with a process of compensation.”