Senior officials from world powers and Iran are gathering in Vienna Friday for the regular quarterly meeting of the so-called joint commission on the 2015 Iran nuclear deal.
Iran said the Vienna meeting between the remaining signatories to the agreement is the "last chance" to save it after the U.S. withdrawal from the pact last year.
Iran is threatening to surpass the maximum amount of enriched uranium allowed by the deal, in response to U.S. economic sanctions imposed in the past year.
Recently, Iran quadrupled its production of low-enriched uranium, but according to an Iranian official the country has not breached the limit.
Tehran has also set July 7 as the deadline for Europeans to offer long-promised relief from U.S. sanctions, or Iran will begin enriching its uranium closer to weapons-grade levels.
European countries are urging Iran to fully comply with the accord.
The Vienna meeting brings together officials from Iran, France, Germany, Britain, Russia, China and the European Union.
Meanwhile, tensions in the Middle East have been rising with U.S. sending an aircraft carrier to the region and deploying additional troops in addition to tens of thousands already there, because of what it says are threats posed by Iran.
