Tommy Sheridan, Dennis Canavan and Robin Harper - dubbed the 'Three Amigos' for their dramatic contribution to the parliament so far - are threatening action of Spaghetti Western proportions.

Socialist Mr Sheridan, the Greens' Mr Harper and former Labour MP Dennis Canavan, who are the only MSPs outside the major party groupings, say they will stage a sit-in.

They currently use three seats behind Liberal Democrat Leader and Deputy First Minister Jim Wallace in the midst of the Lib Dem group.

Dennis Canavan: Former Labour MP

But Deputy Government Business Manager, Lib Dem MSP Iain Smith, has asked the three members to move to seats at the back of the chamber.

Mr Sheridan, MSP for Glasgow region and a former poll tax rebel, attacked the move as "Stalinist".

He said the trio are being moved because they are too near the front and are attracting too much publicity, adding: "I, along with Dennis and Robin, will be fighting the control freaks all the way to make sure we get our rights in the parliament.

"I will not be marginalised by New Labour and I will be prepared to use action including direct action to secure our rights."

Mr Sheridan added: "It will be what we used to call a sit-in during the days of the poll tax. But it will probably be one of the most comfortable sit-ins I have taken part in."

Robin Harper: Britain's only Green parliamentarian

In a letter to Mr Sheridan, Mr Smith said the current seating arrangements were temporary and suggested the three could have seats together at the end of aisle towards the rear of the chamber.

Mr Sheridan said: "There is no way we are accepting this. It would be much more suitable if the puppets went and sat beside the puppet master - if Jim Wallace went and sat beside Donald Dewar."

Speaking to BBC News Online, Mr Sheridan laughed at references to the Three Amigos and added: "We might be 'The Good, The Bad and The Ugly' but I wouldn't like to say which is which!"

Mr Sheridan went on the offensive on the first day of the parliament - giving the oath of allegiance to the Queen but only under protest.

Mr Canavan underwent an acrimonious split from Labour after the party failed to select him as a Scottish Parliament candidate.

He is now a fierce critic of Labour but broke parliamentary protocol by crossing the floor of the chamber to congratulate Scottish Labour Leader Donald Dewar on his appointment as First Minister.