Rebel MP George Galloway last night vowed he would stand against Labour as an independent after being thrown out of the party for his outspoken opposition to the war in Iraq.

Labour's National Constitutional Committee found Mr Galloway guilty of four out of five charges brought against him by the party's leadership.

He denounced the two-day hearing as a "political show trial" which had been rigged in advance by Prime Minister Tony Blair.

Mr Galloway warned he may quit his seat to force a by-election in which he would challenge Labour as an independent candidate.

The Glasgow Kelvin MP's Labour membership was suspended after 36 years in May following an interview on Abu Dhabi TV in which he accused Mr Blair and United States President George Bush of invading Iraq "like wolves".

Labour's ruling National Executive Committee insisted he was being called to account, not for his anti-war views, but for conduct likely to bring the party into disrepute.

He was charged with urging British troops to defy orders, calling on Arabs to attack British troops, telling voters in Plymouth not to support Labour candidates who backed the war, congratulating an anti-war candidate who defeated Labour in Preston and threatening to stand against Labour himself.

Following yesterday's decision in London, Mr Galloway insisted he had been singled out for expressing opinions shared by millions of Labour voters and many of the party's MPs.

He said: "The Labour Party will rue the day they took this step.

"Mr Blair's response to the mistake of the war is to attack those who stood against the war and root them out of British politics. That's a very serious mistake because we are not going to go away."

Rose Burley, chairwoman of the NCC panel, said: "The decision of the panel was that Mr Galloway be expelled from membership of the Labour Party forthwith."

Mr Galloway's expulsion sparked anger among Labour left-wingers and opponents of the war. The chairman of his constituency Labour Party, Mark Craig, said he would give Mr Galloway his "full support" if he stood against Labour as an independent.

Veteran Labour statesman and former Cabinet minister Tony Benn, who gave evidence to the tribunal in support of Mr Galloway, said: "George is a principled and courageous man who opposed the war, as did the Pope and UN Secretary General Kofi Annan.

"What hope is there for the Labour Party if the public think that when you join you just become a private in Mr Blair's army and have to obey orders or be thrown out?"