Embattled U.S. Democrat Anthony Weiner has announced he is resigning from Congress, succumbing to intense political pressure following a scandal in which he sent lewd photos and explicit messages to a number of women.

Weiner's announcement, made at a news conference in his home district of New York on Thursday, was met by several jeers in a room packed with reporters and at least one heckler.

The 46-year-old politician apologized once again for the embarrassment his "personal mistakes" had caused, adding that he had hoped to continue working for his constituents.

"I make this apology to my neighbours and my constituents, but I make it particularly to my wife, Huma," Weiner said.

His pregnant wife, Huma Abedin, is a senior aide to Secretary of State Hillary Clinton. Abedin was not by her husband's side for the announcement.

Weiner said "the distraction" that he created had made it "impossible" for him to continue in Congress.

He had been on leave from the House of Representatives, spending time at an undisclosed treatment facility in the hopes of weathering mounting pressure to quit.

As recently as Saturday he had told reporters he intended to continue serving in Congress.

Weiner's personal problems began nearly three weeks ago when a conservative website called BigGovernment.com published a lewd photograph purporting to show Weiner's groin, clothed in underwear. The photo had been sent from Weiner's Twitter account, the website alleged.

The congressman initially denied the report, claiming that his account had been hacked. But on June 6 he held a press conference, saying that he had engaged in online activity involving at least six women.

House Democratic Leader Nancy Pelosi initially demanded the House ethics committee investigate the scandal. However, over the weekend she changed her position, joining a number of other party leaders in calling for Weiner's resignation.

A special election is expected to be held to fill Weiner's post once his resignation has been submitted.

Time will tell whether Tuesday's announcement marks the end of Weiner's political career. He ran against Michael Bloomberg in New York's 2005 mayoral election and was considered to be a contender to succeed him.

With files from The Associated Press