The Iranian government wants assurances that economic incentives that were part of a landmark deal to stop the country developing nuclear weapons will be protected, despite the U.S. withdrawal and threat of sanctions against companies who trade with Iran.

A senior Iranian official says Tehran expects European Union countries to put forward concrete solutions by the end of May to keep the 2015 Vienna accord alive.

The official briefed a small group of reporters on condition of anonymity ahead of talks Friday in the Austrian capital.

He said failure to find a solution could prompt Iran to resume its nuclear program.

The meeting between Iran, Britain, France, Germany, China and Russia comes after the U.N. nuclear watchdog said Thursday that Tehran appears still to be complying with the accord.