British Defence Secretary Michael Fallon has resigned from his position, saying he accepted his conduct in the past had fallen below high standards.

Mr Fallon was named in an a newspaper article earlier this week that said he had touched a radio presenter's knee in 2002.

The BBC reported on Monday that a spokesperson for Mr Fallon said he had apologised for the incident at the time, while the presenter concerned tweeted that she considered the matter closed.

In a letter to Prime Minister Theresa May, Mr Fallon 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.

"I have reflected on my position and I am therefore resigning as Defence Secretary."

Mr Fallon said that he would continue to serve as a member of parliament.

Mrs May responded to the resignation by thanking Mr Fallon for "a long and impressive ministerial career".

"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," she wrote in a letter.

Mrs May has called for rules on MPs' behaviour to be toughened after the emergence of several allegations of sexual harassment at Westminster.

She has said that action would be taken when there were allegations and evidence of sexual misconduct.