TEHRAN, IRAN — Brazil’s president met with Iranian leaders Sunday to try to broker a compromise in the international standoff over Tehran’s nuclear program, even as the U.S. says new sanctions are the only way to force Iran’s cooperation.

Luiz Inacio Lula da Silva is trying to use Brazil’s friendly relations with Iran to show it can be a fair, neutral broker in the escalating dispute. Since evidence of a clandestine Iranian nuclear program first emerged in 2003, negotiations with world powers and visits by U.N. inspectors have failed to persuade the U.S. and its allies that Iran is not pursuing a weapons capability.

Washington has taken a hard line, and Russian President Dmitry Medvedev said last week that the Brazilian leader’s efforts might be “the last chance” to avoid sanctions.

Silva is reportedly trying to revive a U.N.-backed proposal in which Iran would ship its stockpile of enriched uranium abroad to be processed further and returned as fuel rods for a medical research reactor.

“It’s more difficult for someone who has nuclear weapons to ask someone not to develop nuclear weapons,” Silva said in an interview with Al-Jazeera TV on Saturday. “It’s easier for someone who does not carry nuclear weapons, like myself, to ask for that.”

Like Brazil, Turkey is trying to bring Tehran back to the negotiating table. Turkish Prime Minister Recep Tayyip Erdogan suggested Sunday before departing for Tehran to join talks on Iran’s nuclear program that the uranium swap could take place in Turkey.

“We will find the opportunity to start the swap process. That is why I am leaving,” he told reporters. “If the swap is going to take place in Turkey, we thought we should be there, too. We have heard that a clause is being added.”

“God willing, we will find the opportunity to overcome the problem,” he said.

On Sunday, Silva met with Iranian President Mahmoud Ahmadinejad and Iran’s supreme leader, Ayatollah Ali Khamenei, but the leaders did not make any public statement about the nuclear issue.

Instead the Iranians focused on mutual relations and praised Brazil for maintaining its independence in a world dominated by a few countries.

“Iran and Brazil are two emerging powers, and many of the world’s future issues will depend on how these two countries interact,” Ahmadinejad said. “Brazil and Iran belong to the future while the system of domination (led by the U.S.) belongs to the past.”