UN Security Council member Brazil demanded on Tuesday that Iran guarantee its nuclear programme has no military aims, saying the crisis has become the single most important security issue in the world.

Brazilian Foreign Minister Celso Amorim said his country will work to avoid new sanctions against Iran, but urged Tehran and world powers to show "flexibility" over an atomic fuel deal stalled for several months.

He also objected to the structure of the group of nations negotiating with Iran over its nuclear programme, and indicated that nations such as Brazil and Turkey can be "political guarantors" to resolve the crisis.

"Iran should have peaceful nuclear activities, but the international community should be given guarantees that there will not be violation and diversion (of nuclear technology) towards military aims," Amorim, who is on a two-day visit, told a Tehran press conference.

Brazil, a temporary member of the 15-strong Security Council, has consistently defended Iran's nuclear programme.

But on Tuesday, Amorim said guarantees were necessary as the Iranian nuclear crisis "is the single most important security issue in the world today" and it was obligatory for council members such as Brazil and Turkey to ensure that it is resolved.

"Everybody has to give guaranteees. It could be by way of more (UN) inspectors (on the ground in Iran) and inspections of facilities," he told reporters from Western news media in a separate briefing.

"There are other ways of giving assurances that there are no deviations (of nuclear work) and at the same time giving satisfaction to Iran."

Amorim insisted that the impasse, which has "dragged for seven years," must be resolved.

"We want a solution to this impasse. Brazil is interested in having a role in settling Iran's nuclear issue. I heard the explanation from Iranian sides in my long meeting (with Iranian Foreign Minister Manouchehr Mottaki). It was constructive," he said.

The minister took serious exception to the presence of Western countries in the P5+1 group negotiating with Iran. The group consists of permanent Security Council members Britain, China, France, Russia and the United States, plus Germany.

"Why P5 plus one? Forget about Brazil, why not a European country which is nearer and able to understand Iran ... It has always been like the West will resolve this question," he said.

"We accept China and Russia because they are permanent members and have veto powers anyway so they can come to discussion, but apart from that no other country."

He said Brazil and Turkey could be possible "political guarantors" to help resolve the issue, adding that Ankara could even be the host to exchange nuclear fuel as part of a UN-drafted deal that has been stalled for months.

Later on Tuesday, Ahmadinejad told Amorim during their meeting that "Iran and Brazil have to play a big role in setting up a new just world order," the official IRNA news agency said.

For his part, the Brazilian reiterated that it was Tehran's "right like Brazil to pursue a civilian atomic programme."

Earlier, Amorim told IRNA Brazil could consider hosting the fuel exchange if asked to do so.

World powers and Iran have been at loggerheads for months over the deal, which envisages supplying nuclear fuel for a Tehran research reactor in exchange for low-enriched uranium from Iran.

The deal stalled after Iran insisted the two materials be exchanged simultaneously within its borders. That was rejected by the world powers, who accuse Iran of masking a weapons drive under the guise of what Tehran says is a purely civilian atomic programme.

Washington is leading a push for a new set of UN sanctions against Iran.

For sanctions to pass, nine of the 15 UN Security Council members would have to vote in favour and none of the five permanent members veto it.

Amorim told IRNA Brazil would work to prevent the new sanctions, because they are "ineffective" and "the only thing the sanctions achieve is that they hurt people, especially the lower class of people."

fpn-sgh-hif-jds/al