* Sanctions lifting part of the landmark accord
* No confirmation of agreement from six powers
* UK says some issues remain to be resolved (Adds U.S. comment in paragraphs 11-12)
By Marcus George
DUBAI, Dec 31 (Reuters) - World powers and Iran have agreed to start implementing in late January an agreement obliging Tehran to suspend its most sensitive nuclear work, an Iranian official was quoted as saying on Tuesday.
There was no immediate confirmation of the agreement from the six powers - the United States, Russia, China, France, Britain and Germany - or the European Union, which oversees contacts with Iran on behalf of the six.
The reported agreement follows nearly 23 hours of talks between nuclear experts from Iran and the six powers held in Geneva on Monday and Tuesday.
The seven countries have met several times since striking the breakthrough accord on Nov. 24 to iron out practical details and decide when the deal would be implemented.
An Iranian nuclear negotiator, Hamid Baeidinejad, said a date was agreed on Tuesday.
"Based on the conclusions [reached in] the talks held with ...expert delegations, the implementation of the Geneva accord will start in the third ten-day of January," Baeidinejad was quoted as saying by Iranian Press TV.
"The two sides managed to reach an understanding on the implementation of the agreement and now, their views and interpretations are the same," he said.
The EU and British and U.S. governments indicated, however, work remains to be done on how to implement the November accord.
Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton, said the experts would report back to their capitals and contacts would continue to "finalise a common understanding of implementation".
He declined comment on Iran's assertion that there was an agreement on the timetable for implementing the accord.
In Washington, State Department spokeswoman Marie Harf said progress was made in the talks and the sides "expect to finalize the implementation plan soon."
A senior U.S. administration official said an agreement was close.
In London, a Foreign Office spokeswoman said good progress had been made in the latest talks in Geneva, but some issues remained to be resolved. "Our aim is to bring the agreement into force as soon as possible," she said.
Western diplomats have said in the past that Jan. 20 was a possible implementation date, because that is when EU foreign ministers next meet in Brussels and could agree on the lifting of EU sanctions.
Western countries led by the United States fear that Iran's nuclear work has military goals and have imposed years of sanctions on Iran in an effort to force Tehran to curb its nuclear programme.
Iran denies seeking to build an atomic bomb and says its nuclear work is aimed at power generation and medical research.
Under the Nov. 24 agreement, Iran will suspend its most sensitive uranium enrichment efforts and, in return, Western governments will ease some economic sanctions.
The sequence of these moves appeared to be a sticking point in the expert talks, with divisions focusing on how much prior notice Iran will give Western governments that it is meeting its end of the deal before they lift the agreed sanctions.
Iran's deputy foreign minister, Abbas Araqchi, was quoted saying earlier that he was likely to meet Helga Schmid, Ashton's deputy, to further discuss some issues next week.
The technical talks started on Dec. 9 but Iran broke them off briefly after the United States blacklisted an additional 19 Iranian companies and individuals under its existing sanctions.
Iranian officials said the move violated the spirit of the deal but U.S. officials said it did not breach the agreement. (Reporting by Marcus George and Parisa Hafezi; Additional reporting by Justyna Pawlak and Adrian Croft in Brussels, Andrew Osborn in London, Michael Nienaber in Berlin and Lesley Wroughton in Washington; Editing by Angus MacSwan and Cynthia Osterman)