The British Conservative Party leader, Mr William Hague, has moved to head off a party conference revolt by pro-Europeans with a snap ballot of members on the single currency.

The party's estimated one third of a million members will be asked to endorse the leadership's policy of opposing monetary union at the next general election in a postal vote over the coming three weeks.

The move comes amid fears that pro-Europeans - led by former Cabinet heavyweights Mr Kenneth Clarke and Mr Michael Heseltine - were preparing to hijack next month's conference with a series of speeches backing the euro.

Mr Hague said ballot papers would be sent out in two weeks' time and returned and counted in time for the result to be announced before the conference opens in Bournemouth on October 6th.

He said the vote should enable them finally to lay to rest the divisions on the European issue, which continued to dog the party and were a major cause of its downfall at the last general election.

"As long as our party is distracted by endless debates on the single currency we will always have one hand tied behind our back as we fight this government," he told a news conference at Central Office.

"I want to free everyone in the party, whatever their views on the single currency, to fight this government with both hands and provide an alternative to it.

"We now face new challenges and I will not allow this party to become trapped in the past."

However Mr Clarke was dismissive, insisting he would not change his position and that the vote would count for little.

"My view of the national interest will not be changed by the results of a snap vote of party activists. I will have a free vote in Parliament whenever the issue arises," he said.

"I would expect any leader of the Conservative Party to obtain a good majority in an appeal which will be treated as a request for personal backing for the leader from the membership."

He outlined his scorn by saying that he would not even be campaigning in the ballot.

"I prefer to campaign against the Labour Party rather than against members of my own party," he said.

Mr Hague said he had consulted senior shadow cabinet members about the decision to hold a ballot and all had endorsed it.

All party front-benchers would be expected to back the leadership line which effectively rules out joining the single currency for the life time of the next parliament.

Mr Hague, who is planning to campaign intensively in the run up to the vote, said grassroots members were "sick and tired" of the way the rival factions tried to pull policy one way or the other.

"Those differing from party policy on the euro find it hard to win attention for anything apart from their views on this subject, even if they try," he said.

"Those who support the policy find themselves frustrated and confused by false stories and claims about the level of dissent or the imminence of a shift in policy."

Mr Hague telephoned both Mr Clarke and Mr Heseltine shortly before the announcement to tell them what he intended.

However that did little to allay the suspicions of the party's pro-Europeans who saw it as an obvious attempt to wrongfoot them ahead of the conference.

Another former cabinet minister planning to speak at Bournemouth, Mr Stephen Dorrell, said: "We agree that it is not in Britain's interests to join on January 1st, 1999.

"But I believe our future policy should continue to be determined by where Britain's interests lie rather than by an arbitrary timetable."

Ballot papers will be sent out on September 21st and will have to be returned by September 28th. An accompanying leaflet by the leadership will set out the arguments for backing the official line while opponents will be given the chance to produce a similar leaflet with the arguments against.

Senior party figures were predicting a comfortable victory for the leadership although they acknowledged it was unlikely to deliver a knock-out blow against the pro-Europeans.

Labour accused Mr Hague of "panicking" ahead of the conference.