Amber Rudd’s claim she did not know the Home Office had deportation targets has been undermined by a leaked memo, putting more pressure on the home secretary to resign.

An internal Home Office document passed to The Guardian on Friday, said the department had “a target of achieving 12,800 enforced returns in 2017-18” and that this target had been exceeded.

The June 2017 memo from Hugh Ind, the director of the Immigration Enforcement agency, was sent to Rudd and the then immigration minister Brandon Lewis.

On Thursday, Rudd told the Commons that while the Home Office did have deportation targets – she did not know about them. Rudd had initially unequivocally claimed her department had no targets. “We don’t have targets for removals,” she said.

She told MPs after it was revealed the Home Office did in fact have targets: “Some offices are working with them. Unfortunately I was not aware of them and I want to be aware of them.

“I have never agreed that there should be specific removal targets and I would never support a policy that puts targets ahead of people.”

The Home Office has been contacted for comment.

The home secretary is now fighting for her political life in the wake of the Windrush scandal that saw people with the legal right to live in the UK threatened with deportation.

Diane Abbott MP, Labour’s Shadow Home Secretary,  said Rudd should “resign immediately”.

“Amber Rudd either failed to read this memo, and has no clear understanding of the policies in her own department, or she has misled Parliament and the British people,” she said.

Rudd made matters worse on Thursday when she suggested the UK may not leave the customs union after Brexit – a direct contradiction Theresa May’s official position.