Iran's supreme leader urged his country's politicians to show more unity as he warned the West that sanctions imposed over Tehran's disputed nuclear programme would only make the government more determined to pursue it, Iranian media reported.

The sanctions imposed against Iran since the beginning of this year have taken an enormous toll on its economy, which suffers from a weaker currency, rampant inflation and high unemployment.

Ayatollah Ali Khamenei, who is unelected and holds ultimate authority over Iran's foreign policy and nuclear programme, told Iranian officials not to bicker publicly.

Conservative rivals of President Mahmoud Ahmadinejad in parliament have increasingly criticised his handling of the economy and for not preventing sharp rises in food prices.

"The reality is that there are problems, however you must not blame them on this or that party," Khamenei was quoted as saying by Fars News Agency, in a meeting with officials late on Tuesday. "Instead you must solve those problems with unity."

"You should avoid useless disputes and airing these disputes to help preserve the nation's unity ... and officials should know these actions will not bring them any honor or prestige among the people," he said.

Ahmadinejad and his rival, Parliament Speaker Ali Larijani, were present at the meeting.

The United States and European Union have implemented tough sanctions against Iran, including an embargo of its oil, in an effort to persuade Tehran to give up its nuclear programme, which they suspect is aimed at acquiring an atomic weapon.

Iran has repeatedly insisted its programme has only peaceful aims, including generating energy and developing medical isotopes to treat cancer patients.

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Khamenei said the sanctions hurt the West more than Iran, pointing especially to the eurozone crisis.

"The country will pass over the current economic pressures against the Islamic system, for their continuation is not to the benefit of Western nations," he said.

"They (Western powers) explicitly say they should intensify pressure and sanctions to force the Iranian authorities to reconsider their calculations.

"Not only will we not reconsider our calculations, moreover with even more resolution we will continue on the path of the people."

Three rounds of negotiations this year between Iran and major world powers have ended without an agreement, with Iran insisting it has the right to enrich uranium. World powers want Iran to abide by U.N. resolutions which demand it completely cease enrichment.

Khamenei said that in the past Iran had attempted a rapprochement with the West but that it had only led to world powers refusing to recognise Tehran's rights.

"In that era, the Westerners became so presumptuous that even when our officials were satisfied with three centrifuges, (the West) was opposed," he said. "But today there are 11,000 active centrifuges in the country."

Experts in the past have disputed Iran's reported number of active centrifuges - machines used to enrich uranium - citing technical troubles at its nuclear sites that have restrained growth.

The United States has exempted major countries from its latest sanctions, in return for taking steps to cut their imports of Iranian oil. Khamenei said the exemptions were an indication that the sanctions could not continue for long.

"All of these realities show that we must continue in the path of resistance," he said.