A military strike against Iran is not on the agenda and the United States is committed to a negotiated solution to the dispute over Iran's nuclear ambitions, British Foreign Secretary Jack Straw said on Sunday.
Straw also disagreed with comments by Egyptian President Hosni Mubarak who warned that civil war has started in Iraq.
The idea that Washington could launch a nuclear strike against Iran was "completely nuts", Straw said in an interview on BBC television.
Straw was responding to a report by investigative journalist Seymour Hersh in the New Yorker magazine that the US administration was stepping up plans for a possible air strike on Iran. The White House, without denying the report, reiterated that it was pursuing a diplomatic solution to the nuclear row.
The report said the US administration was seriously considering using "bunker buster" tactical nuclear weapons against Iran to destroy its main centrifuge plant.
Military action against Iran was "not on the agenda", Straw said.
"They (the Americans) are very committed indeed to resolving this issue ... by negotiation and by diplomatic pressure. And what the Iranians have to do is recognise they have overplayed their hand at each stage ...," he said.
Straw said Britain, Washington's closest European ally, would not accept a pre-emptive strike against Iran, adding: "I am as certain as I can be sitting here that neither would the United States."
Circumstantial evidence added up to a "high suspicion" that Iran was developing a civil nuclear capability that could be used for nuclear weapons, he said.
"But let's be clear: There is no smoking gun ... We can't be certain about Iran's intentions and that is therefore not a basis on which anybody would gain authority for military action," he said.
But if Iran were to attack Israel or to attack or threaten its neighbours, "that's a very different circumstance", Straw said, adding that Israel would have a right to self-defence if attacked.
Iran insists it only wants nuclear technology for power generation. Washington believes Iran is trying to build an atomic bomb and refuses to rule out an attack to deal with what it says is one of the biggest threats to regional stability.
Straw conceded that there was a "high level of slaughter" in Iraq but said the country had not descended into civil war.
Mubarak said in an interview broadcast on pan-Arab satellite television channel Al Arabiya on Saturday that civil war in Iraq had "pretty much started".