Iran and Western negotiators on Tuesday reported they were nearing an understanding on the details of implementing the landmark interim nuclear accord reached between Tehran and world powers in November.

After nearly 23 hours of talks between nuclear experts from Iran and the six powers held in Geneva on Monday and Tuesday, Iranian nuclear negotiator Hamid Baeidinejad announced the agreement to suspend Tehran’s most sensitive nuclear work would begin in late January.

“Based on the conclusions the talks held with …expert delegations, the implementation of the Geneva accord will start in the third ten-day of January,” Baeidinejad was quoted by Iranian Press TV. “The two sides managed to reach an understanding on the implementation of the agreement and now, their views and interpretations are the same,” he said.

Western diplomats have said in the past that Jan. 20 was a possible implementation date, because that is when EU foreign ministers next meet in Brussels and could agree on the lifting of EU sanctions.

The nuclear accord puts strong limits on Iran’s uranium enrichment program in return for an easing of some international sanctions on Tehran for six months while a permanent deal is negotiated. The United States and its allies believe Iran’s nuclear program is aimed at producing a nuclear weapon, a claim that Tehran denies, saying it is intended only for peaceful purposes, like power generation and medical research.

The sequence of the implementation appeared to be a sticking point in the expert talks, with divisions focusing on how much prior notice Iran will give Western governments that it is meeting its end of the deal before they lift the agreed sanctions.

The past month, experts from Iran and the so-called “5+1” countries — the U.S., Britain, France, Russia, China and Germany — have held several rounds of talks in Geneva to work out details on carrying out the agreement.

State television quoted senior Iranian nuclear negotiator Abbas Araghchi as saying he may meet again with Helga Schmid, a senior European Union negotiator, next week.

The Europeans said there had been progress, but some points still needed to be finalized, without elaborating.

Michael Mann, spokesman for EU High Representative Catherine Ashton, said the experts would now report back to their home governments and contacts would continue “to finalize a common understanding of implementation.”

He said in an email statement that the world powers are “fully committed to an early implementation” but did not elaborate on the time-frame.

A U.S. State Department official said there has been progress in the talks and the teams have taken “a few outstanding points” back to their governments for consultation. “The two sides expect to finalize the implementation plan soon,” the official said on condition of anonymity.

The technical talks started on Dec. 9 but Iran broke them off briefly after the United States blacklisted an additional 19 Iranian companies and individuals under its existing sanctions. Iranian officials said the move violated the spirit of the deal but U.S. officials said it did not breach the agreement.

Under the accord, Iran is to limit enrichment to producing uranium enriched at 5 percent, the level needed to power a reactor to produce electricity. Uranium enriched to around 90 percent is needed to produce a nuclear warhead. Iran would also neutralize its stockpile of 20-percent-enriched uranium, a level used to power research reactors.