The US has said it plans to send a diplomat to Switzerland in early June to meet senior Iranian officials as part of an effort to rekindle wider negotiations over Tehran’s nuclear programme.

The US delegation will be led by Deputy Secretary of State Bill Burns, who led secret US-Iranian negotiations that helped bring about an interim nuclear agreement between Tehran and the major powers in November.

Under Secretary of State Wendy Sherman, the primary US negotiator with Iran, will accompany him on a team that will include senior White House national security staff. The meetings will be held on 9 and 10 June.

Last month, talks between Iran and six major powers stalled as each side accused the other of having unrealistic demands in negotiations aimed at curbing Tehran’s atomic programme in exchange for an end to economic sanctions.

All sides are aiming to meet what is being seen as an increasingly challenging deadline of 20 July to secure a comprehensive agreement.

Further talks with Tehran are set for 16-20 June, with the US set to join the other members of the six-power negotiating group known as the P5+1, which includes the UK, China, France, Germany and Russia.