The United States and Iran have expressed hope that nuclear talks can be accelerated in order to meet a target for a framework agreement in March.
US Secretary of State John Kerry and Iranian Foreign Minister Mohammed Javad Zarif have met in Geneva for six hours of intensive talks.
The meeting comes a day before negotiators from Iran, the five permanent members of the U.N. Security Council and Germany are to resume talks there.
Earlier, Zarif stressed that serious dialogue with the West would be easier if it respected Muslim sensitivities.
"We won't be able to engage in a serious dialogue if we start disrespecting each other's values and sanctities. I think we would have a much safer, much more prudent world if we were to engage in serious dialogue, serious debate about our differences."
Iran and the six world powers have renewed their quest for an elusive nuclear deal after negotiators failed for the second time in November to meet a self-imposed deadline.
A new deadline has been set for June 30 for a deal that would gradually end sanctions imposed on Iran in exchange for verifiable curbs on its uranium enrichment program.
