US officials said they were preparing for the final major military operation of the war in Iraq, an assault o­n President Saddam Hussein's hometown of Tikrit.

But signs were increasing today that an all-out attack might not be necessary amid indications that defenses in the city were crumbling, much as they did in the other major northern cities the coalition won this week.

Ahead of the planned advance by US-led troops, coalition aircraft continued striking Republican Guard positions in Tikrit, and roadblocks were erected to keep Iraqi leaders fleeing Baghdad from reaching the city, the last redoubt of the ruling Baath Party.