Campaigners for electoral reform have sent an open letter to the Lord Chancellor Lord Falconer urging the Government not to kick the issue into the long grass.
A review of the different voting methods used in elections in the UK is currently being undertaken by officials at Lord Falconer's Department for Constitutional Affairs. They are expected to report their findings to a ministerial committee on electoral policy chaired by Deputy Prime Minister John Prescott.
But the chairman of the Make Votes Count campaign, Lord Lipsey, today made clear he did not regard this exercise as fulfilling Labour's manifesto pledge of a review of voting systems.
The review should not be held behind closed doors, but should be "open and transparent", involving public hearings around the country, the publication of reports and the opportunity for debates in Parliament, wrote the Labour peer, who served on Lord Jenkins's commission on electoral reform.
It should consider the recommendations of the 1998 Jenkins Commission report on possible alternatives to the current first-past-the-post system used in Westminster elections, said Lord Lipsey.
And it should hold out the "real possibility" of a referendum on electoral reform, as promised in Labour's 1997 manifesto.
Labour's manifesto for this May's general election committed the party to "reviewing the experience of the new electoral systems - introduced for the devolved administrations, the European Parliament and the London Assembly".
But it stopped well short of promising a poll on changes to first-past-the-post, saying only: "A referendum remains the right way to agree any change for Westminster."
Prime Minister Tony Blair later told Parliament that he could not guarantee that the review would result in a referendum on proportional representation.
In the open letter, Lord Lipsey wrote that he was "glad" that the review process had got under way.