Republican Senator Larry Craig. - File Photo image:33451:0::0

Washington - A US senator announced his resignation Saturday after pleading guilty to charges of disorderly conduct in a men's airport bathroom. Idaho Republican Senator Larry Craig said at a televised press conference in his home state that he would leave his position on September 30.

A number of politicians, including many from his own party, had been openly calling for Craig to resign since the details of his arrest at a Minneapolis airport emerged on Monday.

Craig, 62, was arrested in June in a police sting operation over lewd behaviour and sexual activity in one of the airport's public bathrooms.

He pleaded guilty in August to a lesser charge - disorderly conduct - and paid a 500-dollar fine, according to the Capitol Hill publication Roll Call, which broke the story. Craig was also sentenced to 10 days in jail, which were suspended, and given a year's probation.

"I chose to serve because I truly love Idaho. What is best for Idaho has always been the focus of my efforts, and it is no different today," he said in his resignation speech. "To the Idahoans I represent, to my staff, my Senate colleagues and, most importantly, my wife and our family, I apologize for what I have caused. I am deeply sorry."

Craig, who was joined by his wife and children, apologized that the debacle had distracted him from his political duties, saying his decision to leave was in his constituents' best interest.

"These are serious times of war and conflict - times that deserve the Senate and our full nation's attention," he said. "There are many challenges facing Idaho that I'm currently engaged in, and the people of Idaho deserve a senator who can devote 100 per cent of his time and effort to critical state and national issues."

He said that his legal problems would distract him from his job, prompting his decision to resign. His announcement brought jeers from the crowd, as well as a cry of "We love you Larry" from one supporter.

Republican leaders on Wednesday stripped Craig of his committee posts in the Senate and had reportedly drafted a statement calling for him to resign, the Washington Post reported. The statement was held back because local Idaho Republicans warned it may have had the opposite effect of making his departure more difficult.

He had already resigned from a top post in Republican presidential hopeful Mitt Romney's campaign.

The leaders of his party welcomed Craig's resignation.

White House spokesman Scott Stanzel said President George W Bush spoke with Craig after the announcement, telling the senator he knew it was difficult decision.

"Senator Craig made the right decision for himself, his family, his constituents and the US Senate," Stanzel said.

Senate Republican Leader Mitch McConnell said "Senator Larry Craig made a difficult decision, but the right one. It is my hope he will be remembered not for this, but for his three decades of dedicated public service."

Fellow Republican and senator from Idaho, Mike Crapo, lauded Craig's accomplishments during his 16 years in the Senate.

"It is my hope that as history judges Senator Craig, that his successes, accomplishments and strong leadership for Idaho in Congress are taken in totality, and that those he served so admirably in Congress for five terms in the US House of Representatives and three terms in the US Senate will recall the full measure of the man," he said.

The state's Republican Governor CL Butch Otter will appoint a replacement to fill Craig's seat for the remainder of his term.

Craig on Tuesday made a public apology for bringing a "cloud" over his home state, and said he regretted his guilty plea.

"I did nothing wrong at the Minneapolis airport ... and I regret the decision to plead guilty," Craig said Tuesday. "I am not gay, I never have been gay."

He did not address the allegations or his guilty plea again on Saturday and a statement on his Senate website referred questions on the matter to his lawyer.

Details of Craig's unsavoury episode dominated US news programmes, newspapers and websites, and pressure for him to step down only increased after an audio tape was released of Craig's interrogation by Minneapolis police.

Before entering the Senate in 1991, Craig served four two-year terms in the US House of Representatives and six years in the Idaho state Senate. He had served as the ranking Republican on the Senate Veterans Affairs Committee and was known for his conservative positions, including his stance against gay marriage.