A senior Iranian official commenting on nuclear talks has said, "some 30% of difficult issues remain to be resolved but it is possible to reach a deal by early March".

A Western diplomat also said, "reaching a deal is possible around early March, if all goes well," Reuters has reported. US officials have implied an unofficial deadline to reach agreement by the end of February.

After eight rounds of talks, key bones of contention include Iran’s demand for a US guarantee of no more sanctions or other punitive steps in future, and how and when to restore verifiable restrictions on Iran’s nuclear activity.

A second Iranian official said Tehran was also insisting on being able to seal and store its advanced centrifuges inside Iran, rather than dismantling and sending them abroad, as Western powers have called for.

He said Iran further wants the removal of some 300 extra sanctions on Iranian entities and individuals not related to the nuclear deal.

US President Joe Biden's administration has said it will remove curbs inconsistent with the 2015 pact if Iran resumes compliance with it, implying Washington would leave in place sanctions imposed under terrorism or human rights measures.

US officials have said the Biden administration cannot guarantee that a US government would never renege on the agreement because it is classified as a non-binding political understanding, not a legally binding treaty.

Reporting by Reuters