Major world powers and Iran will hold fresh talks in Vienna on April 22-23 to build on the framework accord reached on Tehran's contested nuclear programme, the EU announced Thursday.

The two sides "will continue work towards a comprehensive solution to the Iranian nuclear issue based on the key understandings reached in Switzerland on April 2," a statement said.

The talks will take place at political director level, involving first Helga Schmid of the EU's external affairs arm and Iranian Deputy Foreign Minister Abbas Araghchi.

They will then be joined by officials from the five UN Security Council members -- Britain, China, France, Russia and the United States plus Germany.

"In parallel, experts will continue the work on the technical details necessary to finalise the political work," the statement said.

Marathon talks in Lausanne last month ran overtime but finally produced a framework political agreement whereby Iran would accept strict controls over its nuclear programme in return for the easing of damaging economic sanctions.

The restrictions are meant to prevent Iran from acquiring a nuclear weapon, as feared in the West, although Tehran insists its programme is purely for civilian use.

The parties now have until June 30 to reach a final accord but they will have to crack some of the toughest issues -- the lifting of global sanctions and a mechanism to reintroduce them if Iran reneges on the deal, as well as research and development and the possible military dimensions of the Iranian programme.