Peers have voted against plans to abolish the lord chancellor's traditional role, insisting that he or she must continue to be fully legally qualified and a lord.

The move followed a two-hour debate on the Constitutional Reform Bill, a government measure that aims to widen the gap between the judiciary and ministers by establishing a supreme court.

Peers said it was vital that the lord chancellor maintained independence from the executive, upheld the rule of law and had a legal training.

The bill returns to the Commons today, when MPs are expected to reverse the decision of the upper house.

Both sides must agree a compromise if it is to become law before the general election.