Expert-level talks between Iran and six world powers resumed Monday in Geneva, after a break for the Christmas holiday, with Iran’s president expressing optimism they would soon bear fruit.

The talks, which come amid fears that the sides may be unable to reach agreement over implementing a high-profile nuclear deal, will last only a day, officials on both sides said.

Before the brief suspension, Iranian negotiators met with representatives from the United States, China, Britain, France, Russia and Germany, from Thursday through Sunday to discuss the on-the-ground implementation of the guidelines established in the November 24 interim agreement.

The deal calls for Iran to curb enrichment and open up nuclear sites to inspection in exchange for eased sanctions.

Iranian President Hassan Rouhani was reported as saying that the deal would be implemented in the next two months, according to the semi-official Fars News which quoted a member of the Iranian parliament who had attended a meeting with Rouhani.

“Mr. Rouhani referred to the Geneva negotiations and said the negotiations will yield positive results in the next one to two months and then we can have development in the country’s economy,” Jabbar Kouchakinejad told the news agency.

However, Iran’s Deputy Foreign Minister Abbas Araqchi told Iranian state television on Sunday that the talks have run into trouble. He said there are “incorrect interpretations” in settling a protocol to implement the deal.

“Priorities should be decided to make it clear what actions should be first and what should be done later,” Araqchi said. “But the principle of simultaneous actions by both sides is a main dominant standard in the talks.”

Araqchi also referred to a parliamentary proposal that would force his government to increase uranium enrichment to 60 percent if new sanctions are levied, saying it must be implemented if it is approved. The proposal is viewed as a response to a US Senate plan to impose more restrictions on Iran.

“The decision is up to the parliament,” said Araqchi.

Lawmakers proposed the bill Wednesday and so far some 200 lawmakers reportedly have endorsed it. It has yet to be put on the parliament’s agenda.

Iranian Foreign Minister Mohammad Javad Zarif expressed hope the talks will conclude “sooner or later,” in a joint Tehran press conference with visiting Italian Foreign Minister Emma Bonino on December 22. He said the current expert-level talks in Geneva were “slowly” moving forward.

In the meantime, Iran has delayed starting up 1,000 new centrifuges, state television reported nuclear chief Ali Akbar Salehi saying Sunday.

The Iranian delegation met with the six world powers in Vienna on December 12, but cut the meetings short following a decision by the US government to blacklist 19 companies for evading Iranian sanctions.

The delegation flew back to Iran a day before negotiations were set to end, stating that the US’s move violated the interim agreement. In spite of the move, the Iranians resumed talks days later in Geneva.

The West fears Iran is pursuing nuclear weapons under its rogue nuclear program. Iran says the program is for peaceful purposes like power generation and medical research.

Times of Israel staff contributed to this report.