(Bloomberg) -- Diplomats seeking to end a nuclear dispute that’s defined Iran’s ties with the world for more than two decades resumed talks on Sunday with a self-imposed deadline just 60 hours away.

Talks between the Persian Gulf nation, which holds the world’s fourth-largest oil reserves, and world powers continued for a fifth day in Lausanne, Switzerland. In a sign of progress still to be made, U.S. Secretary of State John Kerry canceled engagements in Boston on Monday in order to extend his stay.

A negotiated accord -- even if only a political framework - - could be a major stepping stone to ending Iran’s isolation and rebuilding its global trade ties. Failure would not only deny President Barack Obama and others a major foreign policy success but also raise the prospect that he or a successor would turn to force to prevent Iran from producing nuclear weapons.

“An agreement with Iran -- like the opening to China many years ago -- offers the possibility of avoiding another costly conflict, while beginning the process of reintegrating the revolutionary nation of Iran back into the community of responsible states,” said Gary Sick, a former U.S. National Security Council member who advised three presidents.

Sunday’s talks began with Kerry meeting Iranian Foreign Minister Mohammad Javad Zarif. They were joined by U.S. Energy Secretary Ernest Moniz and Ali Akbar Salehi, Iran’s top scientist in charge of its nuclear program.
Joining Oil Market
If a deal is reached, Iran could add its stockpiles into an oversupplied oil market where prices have fallen more than 50 percent since June. Iran has stored excess crude on tankers for the past 2 1/2 years as restrictions deterred buyers, according to the International Energy Agency. The country exports about 1 million barrels of crude per day, down from 2.5 million in mid-2012, IEA data show.

Iran’s insistence on an immediate lifting of United Nations sanctions is a main obstacle to securing a framework agreement on its disputed nuclear program by March 31, five European and U.S. diplomats said.

The Western powers negotiating with Iran have proposed lifting UN sanctions in four to six years, according to the officials who asked not to be named, in line with diplomatic rules. Some sanctions may remain in place for as long as a decade, they said.

The Chinese foreign minister, Wang Yi, is expected to offer new proposals, according to two people involved in the talks. China in an earlier round of talks this month proposed ways to address lifting UN sanctions.

The sides are working against a self-imposed end-of-March deadline needed to set up a comprehensive deal by July 1.
‘Really Serious’
Iran wants sanctions to be lifted once it agrees to place curbs on its nuclear activities. The UN Security Council, the U.S. Treasury Department and the European Union have all levied economic sanctions on the country over its nuclear program.

Zarif told reporters on Saturday that while headway had been made on sanctions relief, there was more to do.

“They have realized that sanctions pressure and an agreement will not go together,” Zarif said. “Germany and France are really serious about reaching an agreement.”
‘Final Steps’
The stakes are also high for Iranian President Hassan Rouhani, elected as a reformer to fix the economy, which has buckled under the sanctions. Rouhani said the removal of penalties must be “a fundamental part of this agreement” and that it was “the other side’s turn to take the final steps,” the Fars news agency reported Sunday.

The European and U.S. approach focuses on first suspending and then permanently removing sanctions over the lifetime of a deal. Oil sanctions could be lifted within months of an agreement if Iran agrees on a deal that limits its nuclear capacity and allows for broader international verification, one European diplomat said.

“Our president has expressly said that the removal of sanctions has to take place immediately when an agreement is reached,” Iran’s Supreme Leader, Ayatollah Ali Khamenei, said earlier this month in his New Year address to the nation. “The U.S. keeps repeating that we’ll sign a deal with Iran and see if it abides, then we’ll remove the sanctions. This is wrong and unacceptable.”
Russia’s View
Earlier on Saturday, Russian deputy Foreign Minister Sergei Ryabkov said that narrowing disagreements put chances of meeting the deadline at “significantly higher than 50 percent.”

“If we don’t manage to agree this time, this shouldn’t lead to a complete reassessment,” because the deadline for a final deal is not until the end of June, Ryabkov said.

Parties are close to an agreement on turning Iran’s Fordo enrichment facility into a medical isotope production center, an official at the talks said. While Iran would be prohibited from enriching uranium at Fordo, centrifuges would be allowed to produce molybdenum and other isotopes, according to the official’s account.

French Foreign Minister Laurent Fabius and German Foreign Minister Frank-Walter Steinmeier, along with European Union foreign policy chief Federica Mogherini, joined Saturday’s talks with Kerry at the Beau Rivage Palace Hotel on the shores of Lake Geneva. Russian Foreign Minister Sergei Lavrov is due in Lausanne on Sunday afternoon.

“Contrary to all the recent sound and fury, an agreement with Iran, which places verifiable restrictions on its nuclear activities into the foreseeable future, is a historic opportunity,” said Sick.

By Bloomberg