Mohammad Baqer Qalibaf, seen by observers as a likely contender in the 2009 presidential elections, warned that the government to act with more prudence amid rising tensions over the Iranian nuclear programme.

"Government officials must pay attention to the grave situation where Iran finds itself on the international scene," Qalibaf said late Tuesday, according to Iranian media.

"The officials of the system need to act with more maturity, intelligence and cunning as it seems the situation will become even more sensitive."

Qalibaf, who became mayor in 2005 after his elimination from the first round of presidential elections, has until now said little on government policy and concentrated his efforts on improving urban life in Tehran.

A traditional conservative, the mayor prefers to present himself as a technocrat who works with people of all political stripes. He has yet to confirm or deny his presidential intentions.

"We could have achieved our objectives for a lesser cost. We do not need to impose an additional cost on society, because of certain methods and declarations, to reach the just demands of the people," he added.

Qalibaf's comments were the latest in a range of remarks critical of the government's policies on the nuclear standoff from leading conservative figures.

There has been exasperation over Ahmadinejad's brushing-off of UN sanctions action as just "pieces of paper" and his refusal to even countenance the possibility of a US military attack.

Former president Akbar Hashemi Rafsanjani said the danger from the United States "exists and is very serious", a flat contradiction of Ahmadinejad's stance.

The powerful former Revolutionary Guards commander Mohsen Rezaie, meanwhile, said the threats of Iran's foes should not be taken as "jokes".

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