Image copyright Sun on Sunday

The speaker of the House of Lords has made a formal complaint against a peer who was filmed allegedly taking drugs with prostitutes.

Baroness D'Souza has requested a standards investigation into Lord Sewel and also referred him to the police.

Lord Sewel is facing calls to quit or be thrown out of the House of Lords.

The peer, who is yet to comment on the claims, has already quit as Lords deputy speaker and chairman of the Lords privileges and conduct committee.

He has been suspended by Labour and could also face a police inquiry.

But Lords sources say he has indicated he does not plan to quit as a peer in light of the Sun on Sunday's footage.

In a letter to Lords Standards Commissioner Paul Kernaghan, Baroness D'Souza referred him to the Lords' code of conduct and asked him to investigate whether Lords' rules had been broken.

New rules

Under new rules which came into force earlier this year, peers can be expelled if they are found to have breached the code of conduct that all members are expected to uphold

The code requires members to act in the public interest, and in accordance with the seven general principles of conduct identified by the Committee on Standards in Public Life - selflessness; integrity; objectivity; accountability; openness; honesty and leadership

But any investigation into the case is likely to take months and will not begin until any criminal proceedings are completed.

In the past, peers have been temporarily suspended for expenses fraud, lobbying scandals and other misconduct but have all ultimately returned to the House of Lords

What are the rules for Lords?

Lord Sewel was appointed as a Labour peer in 1996 but has sat as a non-affiliated (independent) peer since taking up his standards role.

Former Commons Speaker Baroness Boothroyd said he should "take a quiet way out of the back door of the House of Lords".

She told BBC Radio 4's The World at One he had "brought the house into some disrepute", saying that she was "embarrassed and ashamed" and it was "a story you just couldn't make up".

Image copyright Getty Images Image caption Lord Speaker Baroness D'Souza has written to the standards commissioner and the police

Former Ulster Unionist leader Lord Empey said he should be expelled, adding that the procedures for this already existed.

Labour MP John Mann said the 69-year-old should resign from the Lords voluntarily before he was expelled.

Prime Minister David Cameron, speaking on a trip to Indonesia, said: "These are very serious allegations, I think it's right he has stood down from his committee posts."

He said there would be "further questions asked" about whether it was "appropriate" for the peer to be "legislating and acting in the House of Lords".

Media playback is unsupported on your device Media caption David Cameron: Questions will be asked over Lord Sewel's position "if he is found to have acted in this way"

It comes as the Sun published further photographs of the peer in Monday's newspaper, along with details of new footage in which he is said to make disparaging remarks about a number of other politicians.

The original footage released appeared to show Lord Sewel snorting powder from a woman's breasts with a £5 note.

Mr Kernaghan will gather evidence and the cross-party privileges and conduct committee will then decide on a punishment.

Media playback is unsupported on your device Media caption MP John Mann: "Lord Sewel has no choice but to resign from the House of Lords"

Mr Mann said: "He cannot possibly go in front of his own committee and expect a serious hearing.

"He is a disgrace. He should retire and resign immediately.

"A lifetime ban would be the committee's only option. He needs to save them and himself further embarrassment and go now."

The House of Lords (Suspension and Expulsion) Act 2015 - which received Royal Assent only in March and which Lord Sewel himself helped to introduce - allows peers to be barred from Parliament if they breach the code of conduct.

The code maintains that members must "always act on their personal honour".

Biography

Name: John Buttifant Sewel

Age: 69

Title: Lord Sewel, of Gilcomstoun in Aberdeen

Educated at Durham and Aberdeen universities

Worked as a lecturer at Aberdeen University

Joined the House of Lords in 1996

Lords career: Parliamentary under Secretary of State, Scottish Office, 1997-1999, opposition Scotland spokesman 2010, elected chairman of committees in 2012

UK representative to Nato Parliamentary Assembly, 1999-2002

On Monday, the Sun published a picture of Lord Sewel wearing an orange bra and leather jacket while smoking a cigarette, on its front page.

David Cameron, Boris Johnson and the four Labour party leadership contenders were among those criticised by the peer, the Sun reports.

Lord Sewel is said to have described Mr Cameron as "the most facile, superficial prime minister there's ever been", and Mr Johnson as "a joke".

He is also said to have called Scottish MP Alex Salmond "pompous", and claimed the reason former Labour Prime Minister Tony Blair took the decision to go to war in Iraq was "because he fell in love with George Bush".

'Good headlines'

Lord Sewel, a former Labour minister who is now not affiliated to any political party, served in the Scotland Office under Mr Blair's government.

The Sewel convention, which applies to the relationship between Westminster and the UK's devolved parliaments and assemblies, is named after him.

The former senior vice-principal of the University of Aberdeen has been a member of the Lords since 1996.

Lord Sewel's privileges and conduct committee role came with an £84,500 salary and meant he was in charge of proceedings when the Lords considered a bill at committee stage, and was automatically made a deputy speaker.

In a recent blog for the Huffington Post, he said the Lords had taken "major steps" to "protect its reputation and punish misconduct by its members".

"Scandals make good headlines. The requirement that members must always act on their personal honour has been reinforced," he wrote.