(CNN) - UK Defense Secretary Michael Fallon resigned on Wednesday, admitting that his past behavior towards women had "fallen short", as the swirl of allegations about sexual harassment in British politics intensified.
Fallon's departure came after a journalist, Julia Hartley-Brewer, confirmed he had repeatedly placed his hand on her knee at a dinner in 2002.
Hartley-Brewer has repeatedly said she did not regard the incident as harassment, but Fallon hinted in a statement that further allegations could be forthcoming.
"In recent days allegations have been made about MPs' conduct, including my own. Many of these have been false, but I realize that in the past I have fallen below the high standards that we require of the armed forces, which I have the privilege to represent."
The decision is a blow for Prime Minister Theresa May, whose Cabinet is deeply divided over Brexit and whose minority government is propped up in the House of Commons by a small political party from Northern Ireland. Fallon was a key ally, and could be relied upon to provide loyal defenses of controversial policies in frequent media appearances.
Earlier this week, Fallon, 65, apologized to Hartley-Brewer for the 2002 incident. According to Hartley-Brewer, Fallon -- whom she did not name in her initial account -- withdrew his hand after she told him that if he continued, she would "punch him in the face." She has repeatedly said that she does not believe herself to be a victim, writing on her Twitter account last week: "He tried it on, I turned him down. Now move on."
On Wednesday evening, Hartley-Brewer reacted to Fallon's resignation on Twitter and said: "I doubt my knee was the reason." There had not been any further allegations made against Fallon at the time of publishing.
The Tory MP is the first British politician to resign amid the growing Westminster sexual harassment scandal.
Earlier on Wednesday, UK Prime Minister Theresa May ordered an investigation into her deputy, Damian Green, amid allegations of unwanted advances toward a female writer. Green has denied the harassment claims.
Last week, May ordered an investigation into international trade minister Mark Garnier, who reportedly admitted to a newspaper that he asked his personal assistant to buy sex toys and used a sexual slur against her.
The recent allegations of sexual abuse in some British political circles have snowballed after the Harvey Weinstein scandal broke in October. The accusations against Hollywood movie producer Weinstein have led to a platform for victims of abuse around the world to share their experiences, through the viral #MeToo campaign.
The Prime Minister's office has said all allegations of sexual harassment are to be taken seriously and has urged victims of assault and harassment to report it to the police.
In a letter accepting Fallon's resignation on Wednesday, May praised his "diligent service."
She said: "I appreciate the characteristically serious manner in which you have considered your position, and the particular example you wish to set to servicemen and women and others."
Fallon's resignation comes at a politically tumultuous time for May's Cabinet members, who are due to resume Brexit negotiations in Brussels next week.