Deputy foreign ministers of Iran and the 5+1 member states had a public session here on Thursday night.

Zarif arrived in Geneva Wednesday night to hold a new round of talks with his American counterpart in Lausanne on Thursday.

The new round of nuclear talks started on Thursday March 26 in Lausanne and continues until Sunday.

Speaking to reporters in Tehran on Wednesday, Zarif said the negotiating team persists on the elimination of all sanctions, and would make maximum efforts for the next round of talks in Lausanne, IRNA reports.

British Foreign Secretary Philip Hammond will join the Iran nuclear talks in Switzerland this weekend, a foreign ministry spokesman said today. Hammond, who is on a visit to the United States, earlier this week said an agreement was "deliverable" but urged Iran to make "tough decisions".

A spokesman for French Foreign Minister Laurent Fabius, who has warned against a soft deal leaving Iran with the possibility of obtaining nuclear weapons, has said he will join the talks on tomorrow.

The United States is considering letting Tehran run hundreds of centrifuges at a once-secret, fortified underground bunker in exchange for limits on centrifuge work and research and development at other sites, officials have told The Associated Press.

The trade-off would allow Iran to run several hundred of the devices at its Fordo facility and the site would be subject to international inspections, according to Western officials familiar with details of negotiations now underway. In return, Iran would be required to scale back the number of centrifuges it runs at its Natanz facility and accept other restrictions on nuclear-related work, TIME reports.

In Washington the US Senate voted unanimously supporting a non-binding measure to slap new economic sanctions on Iran should it violate terms of any nuclear deal it reaches with world powers.

In a symbolic measure aimed at building pressure on Tehran amid crunch negotiations over its atomic program, lawmakers voted 100-0 on an amendment introduced by Senate Republican Mark Kirk as part of an ongoing budget debate.

It does not carry the weight of law because budget resolutions are not binding legislation, but it signals senators' determination to act quickly should Iran fail to meet any requirements of the interim accord now in place, or a possible final agreement.