Sir Michael Fallon has quit as Defence Secretary following allegations of inappropriate behaviour as he acknowledged he had "fallen below the high standards required" of the role.

The Tory MP for Sevenoaks, which includes Swanley, became the first casualty in the sexual harassment scandal sweeping Westminster after it emerged he had repeatedly put his hand on a journalist's knee during a party conference dinner in 2002.

Sir Michael's name had appeared on the unverified list of sexual misconduct allegations which has been circulating in Westminster.

In his resignation letter to the Prime Minister, Sir Michael said: "A number of allegations have surfaced about MPs in recent days, including some about my previous conduct.

"Many of these have been false but I accept that in the past I have fallen below the high standards that we require of the armed forces that I have the honour to represent."

In her reply to Sir Michael's resignation letter, Prime Minister Theresa May 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."

The 2002 Tory party conference incident involved radio host Julia Hartley-Brewer, who has said she had not regarded the incident as "anything but mildly amusing".

She reacted with shock to Sir Michael's announcement, writing on Twitter "bloody hell" before adding "I doubt my knee was the reason" for his resignation.

Sir Michael's decision to quit came just hours after Mrs May invited Westminster's party leaders to crisis talks on Monday to discuss plans for tackling sexual abuse and harassment.

The Prime Minister said MPs from all parties are "deeply concerned" about allegations that have emerged in recent days as she invited political counterparts to talks on setting up a new "transparent, independent" grievance procedure.

At Prime Minister's Questions she said: "We have a duty to ensure that everyone coming here to contribute to public life is treated with respect."

Asked whether he was worried that more was to come out about his behaviour, Sir Michael told the BBC: "The culture has changed over the years, what might have been acceptable 15, 10 years ago is clearly not acceptable now.

"Parliament now has to look at itself and the Prime Minister has made very clear that conduct needs to be improved and we need to protect the staff of Westminster against any particular allegations of harassment."

"I think we've all got to look back now at the past, there are always things you regret, you would have done differently."