Conservative leader William Hague has already warned that his party will oppose the government's plans for the upper chamber when legislation is introduced in the next parliament.

The Leader of the Lords, Lord Richard, said Labour still hoped to reach agreement with the Tories on future plans.

But he confirmed that if a deal was not possible, the government would bring in a Bill to scrap the voting rights of hereditary peers.

The Bill would also create an "interim" House while the future composition of the Lords was decided.

"Biggest quango in Britain"

Speaking at a conference in London on the future of the chamber, he made clear that the government would use the Parliament Act to force through the legislation if the Tories used their majority in the Lords to block it.

The Act limits the Lords' power to delay legislation to one year.

Lord Richard denied that the House would become the "biggest quango in the country".

"We believe that no one party should seek a majority in the Lords," he said.

A manifesto commitment

"Like the Grand Old Duke of York, they are marching their men to the top of the hill.

"I can only hope that they have the good sense to march them down," he told the conference.

"Quite frankly, the idea of the Opposition wheeling out their army of hereditary peers to try to block the government's fulfilment of a manifesto commitment would itself be a constitutional outrage."

The transformation of the upper chamber is likely to take place in stages.

Legislation is to be published in the autumn outlining the government's determination to press ahead with its manifesto commitment to abolish hereditary peers' voting rights.

Ancient rights to disappear

The plan would see 750 hereditary peers losing the right they have had since the 14th century to sit in the Lords, although they would keep their titles and other privileges.

The Tories insist they are not opposed to ending hereditary peers' voting rights but want to see full proposals before allowing them to go ahead.

Removal of the hereditary peers would leave a House of nearly 500 life peers, plus 26 Church of England bishops and the Law Lords, who would continue to sit.

Lord Richard said: "We need an upper House that is more representative of the people of this country."

He stressed that the reformed House would remain subordinate to the Commons and would have no extra powers.

"The composition is unjustified and anachronistic. It produces gross political imbalance," he said.

"In a modern Parliament, there really should be no reserved seats booked generations ago for a privileged few."

The Conservative leader in the Lords, Viscount Cranborne, said the Tories would fight the removal of hereditary peers unless they were replaced by an element that was "as least as independent".

"Unless stage one and the further reform of stage two happen together, stage two will not happen at all. In private I have heard ministers accept that," he told the conference.