Iran's deputy foreign minister says serious talks about the country's nuclear program cannot happen until trust is restored between Iranian and international negotiators, who are meeting again Thursday in Geneva.

Abbas Araqchi also said that Iran will not suspend its uranium enrichment as part of any deal.

The five permanent members of the U.N. Security Council, along with Germany, want an interim agreement that calls for Iran to stop some of its enrichment activity and accept more inspections in return for limited sanctions relief.

French Foreign Minister Laurent Fabius said Thursday he hopes an agreement can be reached, but that a deal is only possible if it is based on "firmness."

The latest set of talks began Wednesday, building on a first round of negotiations that ended two weeks ago without visible signs of progress. Analysts say those talks failed, in large part because France said the preliminary deal under consideration did not sufficiently curb Iran's uranium enrichment program.

U.S. Secretary of State John Kerry vowed Wednesday that the United States would not accept any deal that lets Iran buy time to increase its nuclear capability.

The White House on Tuesday described the current talks as "an opportunity to halt the progress on the Iranian program...while testing whether a comprehensive resolution can be achieved."

That statement came after President Barack Obama asked key Senate leaders to hold off on any new sanctions against Tehran while the Geneva talks continue.