LONDON (AP) — A key ally of British Prime Minister Theresa May was forced to resign Wednesday after an investigation concluded he made misleading statements about pornographic images found on a Parliament computer in his office in 2008.

Damian Green, who was ousted as first secretary of state, maintains he did not use pornography on his office computers, but he agreed he had not been forthcoming in statements made about the matter in November.

A report by May's Cabinet secretary concluded Green had made misleading statements regarding his knowledge about the indecent images found by police.

"I accept that I should have been clear in my press statements that police lawyers talked to my lawyers in 2008 about the pornography on the computers, and that the police raised it with me in a subsequent phone call in 2013," Green said in his resignation letter, which was made public Wednesday night.

May said she asked Green for his resignation after the investigation concluded he had not been open about the matter.

"I have also carefully considered the report's conclusions in relation to two statements you made on 4 and 11 November which you now accept were inaccurate and misleading," the prime minister wrote in a letter requesting Green to step aside. She said he had fallen short of the standards expected of him.

"It is therefore with deep regret, and enduring gratitude for the contribution you have made over many years, that I asked you to resign from the Government and have accepted your resignation," May wrote.

Green was a vital political ally who acted as a de facto deputy prime minister and supported May in her difficult Brexit negotiations. His removal will cost her an important supporter as she tries to balance competing visions of Brexit within her Cabinet.

Green had claimed earlier he was the victim of a smear campaign. The pornography was found on his office computer during a police investigation of government leaks.

The Cabinet investigation did not yield a conclusion about sexual misconduct allegations writer Kate Maltby made against Green.

Maltby said Green had "fleetingly" touched her knee during a meeting in a pub and later sent a suggestive text after a picture of her wearing a corset appeared in a newspaper.

The cabinet secretary investigation said it was "not possible to reach a definitive conclusion" on whether Green's behavior with Maltby was appropriate wily, but added that her account was "plausible."

Green is among a number of British politicians who have stepped down or been forced out in recent weeks as a wave of allegations of sexual harassment has surfaced.