Although pro-reformers on the government benches backed adopting the proportional electoral system recommended by the commission last week, a string of Labour MPs made speeches declaring their vehement opposition.

Home Secretary Jack Straw opened the debate by signalling a backtrack on the Labour's manifesto promise to hold a referendum in this parliament on the issue.

He told MPs the government would not "rush into holding a referendum".

He said a poll before the next election remained an option but was now "less certain" - partly because the Jenkins Commission had come up with a very complex system that would take time to implement.

Mr Straw admitted he was still implacably opposed to reforming the voting system but added: "This is an issue that should ultimately be decided by those who matter most in our democracy, the British people."

The commission had "performed a very valuable service in setting the agenda for debate," he said. "Now let the debate begin."

'A con-trick'

Liam Fox: "Jenkins is a con-trick"

Shadow constitutional affairs spokesman Liam Fox, replying for the Opposition, insisted the current first-past-the-post (FPTP) system provided accountability, giving voters "a very easy way to send the removal vans around to No 10, as they did last year."

This was "one of the strengths of our system".

A "deeply disturbing" aspect of the Jenkins Commission's proposals was the "two classes of MP" it would introduce - one elected directly, the other through proportional redistribution of votes cast.

Mr Fox attacked the Jenkins Commission process as a fraud and con-trick, with the prime minister playing different sides in the debate off against the other.

'Labour will split'

Labour's Gerald Kaufman, chair of the Commons culture committee, attacked the commission for putting forward a "hopelessly complicated" alternative to FPTP.

He said the reform was "definitely aimed at reducing the number of MPs for my own party," and warned marginal Labour MPs they would lose their seats.

He insisted Labour would be split in a referendum, while the Tories would be united against it.

Alan Beith: "Perverse results under the current system"

For the Liberal Democrats, Alan Beith told MPs that FPTP produced perverse results, "under-represents minorities ... and denies parties seats in those parts of the country where they have wide support".

The deputy Lib Dem leader said his party could "see no persuasive reason" for delaying the promised referendum.

Labour's Giles Radice told the chamber he entered parliament as a firm supporter of FPTP, but changed his mind "because the Thatcher governments were elected on only a minority of the vote ... but with very large majorities."

Another reason Mr Radice now supported reform was that FPTP discriminated geographically - evidenced most recently by the Tories having no parliamentary representation in Scotland or Wales despite winning a considerable share of the vote.

Benn: Turkeys won't vote for Christmas

Veteran Labour MP Tony Benn defended FPTP as offering voters the best chance of real representation.

He said the Jenkins Commission's plan had " not a cat in hell's chance of succeeding".

He predicted the Parliamentary Labour Party would never vote to "to destroy 50 of its own members ... turkeys do not vote for Christmas."

Labour's Stuart Bell, a leading anti-reformer, also defended FPTP, telling MPs it "has given us stable government, it does give us the constituency link, it is accountable, it also gives us the doctrine of mandate."

Fellow Labour MP Gerry Bermingham branded the commission's proposals lunacy and told the chamber FPTP offered simplicity and "it is the best."

Labour's Martin Salter said while there was a case for change, the commission's proposals "by breaking the link between an MP and his constituents [are] insupportable and will be consigned to the dustbin of history."

Another Labour MP, Claire Ward, said pro-reformers who argued there was a mood for change among voters "are talking, frankly, nonsense".

All through the "many, many years" she had campaigned for Labour, "not one single person has ever said to me that I will vote for the Labour Party because I want proportional representation."

The debate ended without a vote, having been on the technical adjournment of the House - thus allowing, Labour party managers to avoid a potentially damaging vote on the issue.