Refusing to accept the idea that the return of the Britons 12 days after they were seized showed Tehran's readiness to engage the international community, the White House reminded Tehran of the UN Security Council's demands on its nuclear programme.

"I would view the detention of the British sailors as not in line with their willingness to work with the international community," the White House national security council spokesman Gordon Johndroe said, referring to Iran's leaders.

"What would show that they are more in line with the international community is to comply with the UN Security Council resolutions, and suspend their uranium enrichment and reprocessing activities," said Johndroe.

"We'd be hopeful to not have to go back to the UN Security Council for an additional sanction regime," the spokesman said.

And US State Department spokesman Sean McCormack accused Iran of using "hostage-taking as a tool of its international diplomacy."

For its part Tehran Thursday declared its refusal to bow to pressure on its nuclear programme, which it says is for power generation but major Western powers believe is aimed at developing nuclear weapons.