Iraqi troops with at least 50 tanks attempted to break out of the encircled southern city of Basra and launch a counterattack, BBC reported on Tuesday.

Between seven and 20 Iraqi tanks were destroyed or disabled in the fierce battle that broke out, British defence sources said.

Earlier on Tuesday morning, in a change of policy, the British and American forces designated Basra a military target and decided to enter the city to take on the Iraqi troops holed up there.

Till then the allies had planned to avoid all population centres in southern Iraq and head straight for the capital Baghdad.

But the pockets of fierce resistance that they continued to encounter into the sixth day of the war convinced them that they could no longer ignore the troops holed up in these other cities.