Negotiators from the United States and Iran have held face-to-face talks in Geneva in hopes of pushing forward efforts to reach a comprehensive deal on Tehran’s nuclear program.

State Department spokeswoman Marie Harf said in Washington that U.S. and Iranian officials met for more than five hours Monday and the talks are expected to continue all day Tuesday.

Harf said the substance of the discussions was kept private to “give them the best chance of success.”

An interim deal reached in November between Iran and six world powers, the U.S., Russia, China, Britain, France and Germany, limited Iran’s uranium enrichment program. In exchange, some penalties against Iran were eased.

The full nuclear talks are scheduled to resume June 16. There’s an informal deadline of July 20 for a comprehensive deal.

(AP)