TEHRAN – Brazilian and Turkish diplomats are trying to persuade Iranian leaders to deposit part of their uranium stockpile abroad in exchange for recognition of their controversial nuclear enrichment program, Brazilian Foreign Minister Celso Amorim said Saturday.

U.S. officials have blessed the outreach but have said the efforts are the “last big shot” before further sanctions are proposed to the 15-member United Nations Security Council.

Parts of the proposed deal are broadly similar to a U.S.-backed plan last year in which Iran initially agreed to swap its low-enriched uranium in return for specially packed fuel that could be used in medical reactors. That proposal ran aground, however, and the United States has been gathering support for fresh sanctions against Iran.

Brazil and Turkey, temporary members of the U.N Security Council, have been critical of sanctions, saying they do not think the measures would be effective.

There are already three rounds of Security Council sanctions against Iran, all demanding that Iran stop its enrichment program. Iran claims the enrichment is for peaceful energy purposes, but the United States and others charge that it is aimed at developing a weapon.

The Brazilian foreign minister said in an interview that Western nations need to come to terms with the fact that Iran has a nuclear energy program. The Brazilian-Turkish proposal, he said, acknowledges Iran’s right to enrich uranium while guaranteeing rigorous inspections to prevent Iran from using its uranium to make weapons.

“What we need to do is make sure the uranium they produce will not be misused by them,” said Amorim, who was scheduled to be joined in Tehran by Brazilian President Luiz Inacio Lula da Silva late Saturday.

Iranian officials have not committed to the Brazilian-Turkish outreach, but have said they view it positively. “These proposals have the ability to lead to an agreement,” Ramin Mehman-Parast, an Iranian foreign ministry spokesman, said Saturday.

Turkish Premier Recep Tayyip Erdogan, who was widely expected to join da Silva today in Tehran, has canceled his trip.

He said that Turkey had asked Iran to sign a declaration of its willingness to resolve the dispute. “But so far Iran has not taken any step in this matter,” Erdogan told the Turkish news agency Anatolia on Friday.

But according to Amorim, the Iranians now understand the urgency of the situation.

“I think the Iranians understand perfectly well that there needs be a significant gesture,” he said.