SCOTTISH MP Eric Joyce has been suspended by Labour, and his constituents have called for him to stand down, after he allegedly head-butted a Conservative politician in a House of Commons bar.

Police arrested the Falkirk MP after the brawl, in which it is claimed Stuart Andrew, the member for Pudsey, was left covered in blood.

Mr Joyce, an ex-Army major, is alleged to have assaulted Mr Andrew following a row in which he complained the bar was "full of Tories" shortly before 11pm on Wednesday. In the ensuing scuffle it is thought another Conservative MP was shoved and a Labour whip was hit when he intervened.

Last night Mr Joyce was still being held in a central London police station on suspicion of assault.

It was also alleged last night that Mr Joyce was involved in another incident after he was taken into police custody.

Officers spent yesterday questioning fellow MPs and other potential witnesses in their offices at Westminster.

Mr Andrew was allegedly head-butted during the row, which took place in the Strangers' Bar at the Palace of Westminster.

A Tory source claimed that Conservative Alec Shelbrooke, another West Yorkshire MP, was caught in the crossfire.

The source said Mr Shelbrooke had blood "all over his shirt" after the incident.

It is thought Phil Wilson, the Labour whip, was also hit as he tried to calm Mr Joyce down.

Eventually Jackie Doyle Price, Conservative MP for Thurrock, also intervened and the police were called.

There were also reports he

had taken exception to being told to quieten down after starting to sing.

Even if he is charged and found guilty it is thought unlikely the incident will trigger a by-election in Falkirk. MPs are only forced to stand down from their seats if they are sentenced to serve a year or more in jail.

Last night friends of Mr Joyce expressed concern for the MP and said he had been struggling with a number of personal issues.

A Labour source said: "It is very sad. He has not been well for some time".

In his constituency, one voter said, if the assault allegation was true, "I don't think he should be an MP".

Mr Joyce, a former soldier in the Black Watch, stood down as a parliamentary aide to Defence Secretary Bob Ainsworth in 2009, citing concerns over the war in Afghanistan.

In 2010 he resigned from his position as Shadow Northern Ireland Minister after being fined £400 for failing to provide a breath test following a motoring incident.

A Labour statement said: "This is an extremely serious incident. We have suspended Eric Joyce pending the results of the police investigation."

Mr Joyce will not be allowed to take the Labour whip until the police have finished their investigations.

Commons Speaker John Bercow thwarted any attempt to raise the matter in the chamber by issuing a stern warning at the start of proceedings. He said it was being investigated, adding: "I take this matter very seriously, as do the House authorities."

Yesterday Mr Andrew took to his Twitter account to reassure well-wishers that he was "OK" after the incident.

Mr Andrew defected from the Tories to Labour in 1997 but rejoined the Conservatives and entered Parliament in 2010. Openly gay, he was the victim of a homophobic attack in the late 1990s and spoke of the "fear" that stayed with him after the incident.