Mr Hain does not back proportional representation but wants an Alternative Vote (AV) system, meaning MPs would need 50% of the votes to get elected.

"AV will give voters a greater sense of influence and ownership over the political process," he said on Tuesday.

However, No 10 says the cabinet has not discussed the issue in recent months.

Second choices

The government set up a Royal Commission on voting reform during its first term but since then the issue has lain in the long grass.

Labour's National Policy Forum is due to discuss voting reforms later this week.

Commons leader Mr Hain said the party needed to make electoral reform a manifesto commitment but campaigners had to work hard to ensure it was the right one.

Speaking at a meeting organised by the Make Votes Count group at the House of Commons, he said the issue was "not going to go away".

Under Alternative Vote, people rank all candidates in order of preference.

At the count, if no candidate has the support of at least half the electorate, the bottom candidate is knocked out and their votes reallocated according to second preferences.

The process continues until one candidate has a majority.

'No panacea'

Mr Hain said the system kept the single member constituencies which made MPs accountable to local people while providing a fairer reflection of votes cast.

"A new system like the Alternative Vote will improve the incentives to vote and remove many of the barriers inherent in the current system," he argued.

Turnout was a problem, especially in safe seats, said the minister.

But people's increased involvement in writing to MPs, signing petitions or attending demonstrations showed their interest in politics.

He acknowledged electoral changes were not a panacea for disengagement, but said the existing system was not helping.

'No cabinet talks'

And he saw increased evidence of tactical voting which meant "you are forced to vote for a candidate you do not much like in order to get rid of a candidate you really cannot stand".

He also had a warning for progressive voters who may "vote Liberal Democrat or Green because they think they can have a free hit at the government, because they may be upset over Iraq or some other issue".

"In the very close marginal seats ... you will effectively lose the election for the Labour sitting candidate and get the Tory elected," he said.

The minister also urged advocates of proportional representation to realise MPs would not vote for a system which would lose many of them their jobs.

Asked about Mr Hain's call for change, Tony Blair's official spokesman said the government's position remained unchanged.

"We have a commitment to have a look at this after this year's elections.

"Obviously we will look at it carefully. But I am not aware the cabinet has discussed this in the last couple of years, certainly not in recent months."

The Royal Commission on the issue recommended an AV Plus system, where voters would also get another extra vote on a county basis to choose around 150 MPs.