Undersecretary of State Wendy Sherman will lead a US delegation to Vienna May 13 to join the next round of negotiations on finalizing an Iran nuclear accord, the State Department said Monday.

The American team, which includes a representative of President Barack Obama's National Security Council and experts on arms control, non-proliferation, economic sanctions and energy, departs Wednesday.

The European Union and Tehran said in a statement last week that the crunch talks aimed at hammering out a final deal by a self-imposed deadline of June 30 were to resume Tuesday in the Austrian capital.

The EU negotiator Helga Schmid and her Iranian counterparts would kick off the talks, with political leaders of the other world powers involved in the negotiations joining in on May 15, the statement said.

The so-called P5+1 group -- Britain, China, France, Russia and the United States, plus Germany -- is conducting the sensitive negotiations aimed at preventing Iran from developing nuclear weapons, in exchange for an easing of punishing economic sanctions.