Tehran/Vienna: Iran’s chief nuclear negotiator Abbas Araqchi Friday slammed a move by the US to expand its sanctions blacklist, saying it went against the spirit of a landmark nuclear deal.

“America’s move is against the spirit of the Geneva deal,” under which world powers agreed not to impose any new sanctions, Araqchi told the Fars news agency.

“We are evaluating the situation and will make the appropriate response,” he added.

Meanwhile, a spokesman for the EU foreign policy chief Catherine Ashton said talks on implementing the nuclear deal have been interrupted for further consultations in the expectation they will resume “soon”.

“After four days of lengthy and detailed talks, reflecting the complexity of the technical issues discussed, it became clear that further work is needed,” spokesman Michael Mann said.

“There will now be consultations in capitals, in the expectation that technical talks will continue soon,” he said.

The statement came after Iranian state media reported that Tehran’s negotiators had returned home after Washington blacklisted a dozen companies and individuals for evading US sanctions.

Under a deal struck in Geneva on November 24 world powers agreed not to impose fresh sanctions during a six-month roll-back of parts of Iran’s nuclear programme.

Senior US administration officials argued however that Thursday’s measures were taken as part of the existing sanctions regime.

The talks in Vienna, which began on Monday, involved experts from Iran and the P5+1 world powers - the US, China, Russia, Britain, France and Germany - plus the International Atomic Energy Agency, which will verify Iran’s freeze.

Once the starting gun fires on the six months, Iran and the P5+1 are due to negotiate a long-term “comprehensive” accord to end once for all the decade-old stand-off over Tehran’s nuclear programme.