A cross-party working group led by Justice Secretary Jack Straw had decided there should be fewer than 400 representatives in the reformed upper chamber, according to reports.

Mr Straw had promised a "comprehensive reform package" in Labour's manifesto for the next General Election and is due to publish a White Paper of proposals.

MPs voted last year in favour of a wholly or 80% elected chamber, in direct opposition to the preference of the present Lords, which wants to retain a fully-appointed chamber.

Discussions were ongoing as to whether the remaining hereditary peers would be removed immediately and the precise how and when the new chamber would be elected, reports claim.

A Ministry of Justice spokesman said: "We will be bringing forward proposals for House of Lords reform in due course. We hope to publish a White Paper before the summer recess.