Jack Straw mounted an 11th hour bid to halt British troops joining the assault against Iraq, a new book is set to claim.

Author and journalist John Kampfner alleges that the foreign secretary sent a memo to Tony Blair following the eve-of-war summit in the Azores.

Straw is said to have warned the prime minister that Britain should offer moral and political support - but no troops - to President Bush.

The foreign secretary added that going to war without an explicit UN mandate would damage British interests.

Blair is said to have flatly rejected the 11th hour call from the foreign secretary.