(Adds quotes, background) LONDON, Feb 22 (Reuters) - British Prime Minister Tony Blair said on Thursday he did not know of any plans for an attack on Iran over its nuclear programme but refused to rule it out completely. A diplomatic solution to the standoff was the only one "anyone can think of" that was viable and sensible, Blair said in a BBC radio interview. But pressed repeatedly on whether an attack was inconceivable, Blair declined to say so. "You can't absolutely predict every set of circumstances that comes about, but sitting here now and talking to you I can tell you that Iran is not Iraq," he said. "There is, as far as I know, no planning going on to make an attack on Iran and people are pursuing a diplomatic and political solution for a very good reason ... that it is the only solution that anyone can think of as viable and sensible," he said. The West fears Iran is trying to make nuclear bombs and missiles under cover of a civilian nuclear energy programme. A U.N. watchdog report due on Thursday is likely to confirm that Iran has escalated rather than halted its nuclear fuel programme, exposing Tehran to wider sanctions. As a 60-day grace period for it to stop enriching uranium expired on Wednesday, Iran offered to guarantee it was not pursuing nuclear weapons, but only as part of negotiations. It has refused to shelve the programme as a precondition for talks. Blair said he could not think that it would be "right" to take military action against Iran. "The question people should be asking me is: What do you do if they get a nuclear weapon? It's a very hard question. Which is why we had better make sure that this political and diplomatic track works," he said.
