LONDON: A British peer who had been in charge of parliamentary ethics quit the House of Lords on Tuesday after allegedly snorting cocaine off a prostitute's breasts, fuelling calls for reform of the unelected upper chamber.

Lord John Sewel, 69, apologised for the "pain and embarrassment" caused after the Rupert Murdoch-owned Sun newspaper published pictures of him apparently taking drugs and wearing an orange bra and studded leather jacket as he chatted to two sex workers.

The images also showed him calling Prime Minister David Cameron "facile" and "superficial" and insulting several other senior politicians.

Scotland Yard has launched an investigation and raided Sewel's home at an exclusive block of flats near the Houses of Parliament on Monday night.

While reforming the House of Lords is not a priority for Cameron's centre-right government, the case has sparked calls in the media for the chamber -- the world's largest legislative assembly outside China -- to be slimmed down.

"I have today written to the clerk of the parliaments terminating my membership of the House of Lords," Sewel, who had been in charge of overseeing the conduct of peers before the scandal broke, said in a statement.

"I want to apologise for the pain and embarrassment I have caused."

The Sun on Tuesday quoted the escorts saying he snorted up to eight lines of cocaine and described one of their sessions.

"He slipped into a woman's blue dress and applied lipstick and eyeliner to engage in depraved sex games too obscene to report in a family newspaper," the tabloid said.

- 'Bloated' House of Lords -

On Monday, Cameron had questioned whether it would be "appropriate" for Sewel to continue approving laws amid the "very serious allegations" against him.

The married 69-year-old, dubbed "Lord Sewer" by The Sun, left his £82,525 (115,000 euro, $128,000) a year post as Lords deputy speaker after the scandal first broke Sunday.

He then announced Monday that he would take a leave of absence from the Lords but faced growing pressure to step down entirely.

Several British newspapers said Tuesday that changes were needed to the House of Lords, made up of 783 peers who can claim a £300 daily attendance allowance, in the wake of the case.

Most members are former ministers appointed by their own political parties and Cameron is reportedly set to create a string of new peers from his Conservative party to give him a majority in the upper chamber, which scrutinises and rubber stamps legislation.

The Daily Mirror, The Sun's main tabloid rival, launched a campaign Tuesday to get rid of all unelected peers.

Meanwhile, The Times said the House of Lords was "bloated" and its numbers should be reduced.

"An unelected chamber with esoteric practices and a median age of about 70 cannot afford to enter the public consciousness only when its members are embroiled in scandal," it said in an editorial.

 String of previous breaches 

Leader of the House of Lords Baroness Tina Stowell acknowledged the importance of public perceptions of the chamber as she welcomed Sewel's resignation.

"For the House of Lords to earn the confidence of the public, all of us must respect the privileges that come with a peerage and recognise that, because we are unelected, it is especially important to meet the standards the public have a right to expect," she said.

Sewel is a former academic and local politician in northeast Scotland who was appointed as a junior agriculture minister in Tony Blair's centre-left Labour government in 1997.

He gave up the Labour whip in 2012 when he took on the job of overseeing the conduct of peers.

Ironically, Sewel oversaw the introduction of a new system under which peers can be ejected from the House of Lords for breaching a code of conduct. Previously, only the monarch could eject them.

Ten members of the Lords have been temporarily suspended since 2009 for breaches including abusing the expenses system and being caught by undercover reporters offering to lobby for private companies.