On today's menu: Nile perch and Blair's downfall

Challenge from the left: Rebels meet at smart restaurant to prepare for battle with 'authoritarian' Government

Labour dissidents held a mock Last Supper for New Labour as the left geared up for a power struggle with Tony Blair's leadership of the party.

In a private room at the Cinnamon Club, a Westminster restaurant favoured by New Labour apparatchiks, the group which calls itself the Old Testament Prophets discussed a fantasy reshuffle.

The MPs, who included former minister Peter Kilfoyle, Bob Marshall-Andrews, Martin Salter, Ian Gibson, and Derek Wyatt, poked fun at New Labour over the mince kebab with peppers, Nile perch with spiced onion and tomato sauce, washed down by the house Languedoc.

The founder of the group, Mr Marshall-Andrews, jokingly put himself forward as a replacement for the embattled Transport Secretary, Stephen Byers.

He lampooned the Government's privatisation of air traffic control with a one-man sketch worthy of Monty Python, suggesting a spoof alternative involving plane-spotters at the coast armed with binoculars and mobile phones.

With The Independent on Sunday also there, one Labour MP on the top table spoke of the "ice unpacking" around the body of New Labour. Another said Mr Blair was not unassailable – he was "unsaleable" to the voters for a third term.

But behind the ribald humour – mostly at Mr Blair's expense – lay growing dissent over the direction of the Government. Lynne Jones described Mr Blair as a Tory.

Tony McWalter, the Labour MP who caught Mr Blair out at Prime Minister's Questions by asking him about his philosophy, said Mr Blair was in charge of a "deeply authoritarian system", which did not value individual thinking.

The Government will be able to shrug off the good-humoured jibes from the Old Testament Prophets as end-of-term high jinks before the Easter recess, but some left-wing MPs fear there will be a crackdown to stop the rot.

Alarmed by speculation of a challenge to Mr Blair, government sources said troublemakers will not be given Labour support in their constituencies. They will be denied visits by ministers unless they toe the line.

But the GMB trade union has threatened to reciprocate by pulling its support from candidates in the local government elections in May unless they back the union's stance on public services. A letter was sent out by the GMB to all Labour councillors last week. A spokesman said the union was fed up with New Labour "screwing our members".

A group of about 40 hard-line leftwingers are preparing a more direct challenge to Mr Blair. The Campaign Group of Labour MPs has told the IoS they are planning a "relaunch of the left" at a TUC conference on 20 July. They are holding an event at the conference called "After New Labour" attended by trade union leaders and Labour MPs.

"It is a relaunch. New Labour is finished. That is what we will be saying, and we want to go forward in a socialist direction," said a spokesman for the group.

Mr Blair is expected to use the Budget and higher spending on the health service to silence his critics and regain a grip on the party after Easter.

However, there is growing dissent over the threat of war with Iraq, the privatisation of public services and job losses in the Post Office.

There is also a power struggle being mounted for the chairmanship of the TUC following the announcement by the Blairite John Monks that he is stepping down to stand for a European union role.