A legal challenge to the home secretary's anti-terrorism powers, which begins in the House of Lords today, is reported to be behind a delay to their reform.

David Blunkett had hoped to be able to include new measures allowing for security services' bugging transcripts to be heard in court, reducing the need for internment without trial, in November's Queen's speech.

But the legislation will now have to wait for a later chance to pass through parliament as the impact of the challenge is assessed.