Electoral reform campaigners have dismissed reports of a possible Lib Lab deal over reforming Westminster's electoral system.

A pledge in the Labour manifesto will promise a review of the way PR has worked in Scotland and Wales after their 2003 elections. If a case for change is apparent, a referendum will be held on whether to opt for Lord Jenkins' "alternative vote plus" system.

The Lib Dems have promised they will "continue to keep up the pressure" for electoral reform, according to party leader Charles Kennedy, as the offer falls well short of his party's commitment to holding a referendum on PR in the next parliament.

Despite opposition from within the cabinet Tony Blair has brokered a life-raft deal with Charles Kennedy by which an electoral agreement would be reached if Labour felt it was about to lose the general election after next. The deal is a clear victory for the prime minister over John Prescott who once said he would put the issue "in a boat and sail it away".

The Times claims that Labour's manifesto will say: "We will review experience of the new systems in Scotland and Wales, and the Jenkins report, to assess whether changes might be made to the electoral system for the House of Commons. The referendum remains the right way to agree any change for Westminster".

Conservative Party Chairman, Michael Ancram, accused Blair of cynicism. "This is a breathtakingly cynical attempt by Tony Blair to buy off Charles Kennedy and the Liberal Democrats for an even cheaper price than the promised referendum in the last Labour manifesto, on which he manifestly failed to deliver.

Ancram rounded on Kennedy: "If the Liberal Democrats co-operation can be bought at this price, then it indicates the depth to which that party has sunk under the leadership of Charles Kennedy."

Voting reform group Charter 88 reacted with dismay. Director of Charter 88, Pam Giddy said: "It is now clear that the Labour Party has reneged on its 1997 manifesto commitment to hold a referendum on voting reform for Westminster. What is worse, the Liberal Democrats have let him get away with it."

The group said the issue now had to be "taken out of Westminster" if reform was to ever take place. "Those of us pushing for reform since 1997 have relied too heavily on the goodwill of politicians to deliver a referendum. In the end it was not in their narrow party interest to do so. We should have headed John Smith's advice that this was an issue too important to be left to our elected representatives," said Giddy.

"The entire purpose of electoral reform is to give more power to the voters. Politicians are not too keen on it so, from here on out Charter 88 will be taking the argument directly to the people," said Giddy.