"The officials and the political experts need to avoid provocative and illogical declarations and slogans," Ali Akbar Velayati told the hardline Jomhouri Eslami newspaper in an interview.

He did not mention Ahmadinejad by name but the controversial president has caused alarm both inside and outside Iran with his provocative comments on the nuclear drive.

The comments by Velayati, who is currently foreign policy advisor to Khamenei and served as foreign minister from 1981 to 1997, come at a critical time in the Islamic republic's five-year nuclear crisis with the West.

Six world powers last month submitted a plan to Iran aimed at ending the crisis, offering technological incentives in exchange for Tehran's suspension of sensitive uranium enrichment operations.

"The 5+1 group take into consideration every word of those declarations and slogans and we have to give more careful statements," Velayati was quoted as saying.

"A certain declaration could cause us problems, we need to be careful not to make these declarations," added Velayati, the longest-serving foreign minister in the history of the Islamic republic.

Ahmadinejad has compared the nuclear programme to a train without brakes and asserted that Iran is now the most powerful nation in the world.

He has also shown little enthusiasm about the package offered by world powers.

"Recently they have started a new game -- by testing us -- but this will result in no achievement for them except humiliation," he said in a speech last month.

The president has also been condemned by the West for repeatedly predicting the imminent disappearance of Iran's regional arch-foe Israel, which he has described as a "stinking corpse".

Despite Ahmadinejad's rhetoric, Iranian officials including Foreign Minister Manouchehr Mottaki and parliament speaker Ali Larijani have said Tehran is reviewing the package and will give a response soon.

Velayati also spoke out in favour of negotiations with the world powers.

"Those who are agitating against our interests want that we reject the offer. As a consequence, it is in our interests to accept it," he said.

Underlining the continued sensitivity of the situation, tensions have again mounted in recent weeks after reports that Israel was mulling a strike against Iranian nuclear facilities.

The West and Israel fear Iran could use uranium enrichment to make a nuclear weapon but Tehran says it has every right to master the full nuclear fuel cycle for what it insists is an entirely peaceful drive for atomic energy.

Iran's conservative-controlled parliament warned on Tuesday it would reduce nuclear cooperation if any further sanctions were imposed over the country's atomic drive.

© 2008 Agence France-Presse