The education secretary has issued a warning to Gordon Brown that he cannot presume he will inherit the Labour leadership.

Charles Clarke says in an interview with this week's New Statesman magazine that the chancellor's chances of succeeding Tony Blair will be "determined entirely by how the vacancy arose".

"Nobody is entitled to an automatic inheritance of any description," he adds.

Clarke is seen as one of the few Cabinet ministers who might oppose Brown in any post-Blair leadership election.

His comments are likely to fuel speculation over the succession but could equally be seen as an attempt to play down presumptions on behalf of Brown, to whom he is thought to be close.