Immigration teams were set Home Office targets for voluntary departures of people regarded as having no right to stay in the UK, it has emerged.
On Wednesday Home Secretary Amber Rudd denied targets were used, as she faced MPs investigating the problems faced by the Windrush generation.
An inspection report from December 2015 shows they did exist at that time.
The Home Office said it has never been policy to take decisions arbitrarily to meet a target.
Labour says officials were under pressure to remove migrants to meet the government’s “bogus” target of reducing net migration to less than 100,000 a year.
Leader Jeremy Corbyn said Mrs May’s policy of creating a “hostile environment” for those in the country illegally “swept up British citizens and legal migrants”, such as the members of the Windrush generation, “causing them immense suffering, as she was warned”.
He called on Ms Rudd, who succeeded Theresa May as home secretary in July 2016, to quit over the saga, at Prime Minster’s Questions.
The Windrush row erupted after it emerged relatives of migrants from Commonwealth Caribbean countries who settled in the UK from the late 1940s to the 1970s had been declared illegal immigrants if they could not provide a range of documentation which proved they had lived in the UK continuously.
Some of the Windrush generation have been threatened with deportation, lost their jobs or been refused access to medical treatment.
Prime Minister Theresa May has repeatedly apologised for their treatment – but she insists tougher action against illegal immigrants has public backing and was a policy pursued by Labour when it was in power.
Amber Rudd has also apologised for the Windrush scandal and blamed Home Office officials for not treating people with sufficient respect, saying they needed to “show a human face” and “exercise greater judgement where it is justified”.
Addressing the Home Affairs Select Committee on Wednesday, she said she had asked for more removals of illegal immigrants to take place, but was not familiar with a suggestion from a union official that regional targets were in place.
She said: “We don’t have targets for removals”, adding “if you are asking me if there are numbers of people we expect to be removed that’s not how we operate”.
The home secretary said she would “certainly take a look” at the evidence MPs had heard about targets.
Glyn Williams, a senior civil servant responsible for immigration policy, also said he did not think such targets existed.
The exchange prompted committee chairwoman Yvette Cooper to say the issue needed to be “cleared up” quickly if Ms Rudd and Mr Williams were to avoid claims they were exercising a “lack of grip” on the area.
Lucy Moreton, general secretary of the Immigration Service Union, had told the MPs a national target, broken down regionally, had been set to remove people in the UK illegally, and staff were under “increasing pressure”.
She said the government’s net migration target had been “translated down through the operational arm of the Home Office to a… net removals target that enforcement teams have to meet, so they are aiming to remove a certain number of individuals in any given month”.
The December 2015 inspection report on removals from the Chief Inspector of Borders and Immigration makes clear there had been certain targets at that time.
It says for 2015-16 the Home Office set a target of 12,000 “voluntary” departures of people with no right to remain, split between 19 enforcement teams across the UK.
There was also a target to remove families in the country illegally, though the inspection report said it was not a “useful performance measure”.
There are three types of enforceable departures: deportations, administrative removals, and voluntary departures.
The term “voluntary” describes the method of departure rather than the choice of whether or not to depart, the Migration Observatory explains. Those leaving in this way are able to approach the Home Office for financial assistance with their travel arrangements.
In her evidence to the committee, Ms Rudd rejected suggestions that the Conservatives’ goal of reducing net migration below 100,000 had contributed to the Windrush problem.
“The problem here is that people were not properly documented,” she said.
The government has set up a task force to help those affected by the Windrush cases formalise their status.
So far 3,800 calls have been made to the helpline, of which 1,364 were potentially Windrush cases, MPs were told on Wednesday.
Ms Rudd told the Commons Home Affairs Committee that she had known about the problem for months and said officials were still checking how many people had been detained over their supposed immigration status.
“I bitterly, deeply regret that I didn’t see it as more than individual cases that had gone wrong that needed addressing, ” she said. “I didn’t see it as a systemic issue until very recently.”