A landmark nuclear deal between Iran and six world powers is being implemented as planned but much remains to be done to resolve all issues regarding Tehran's atomic activities, the UN nuclear chief said on Monday.

Yukiya Amano, director general of the International Atomic Energy Agency, also said the IAEA remained 1.6 million euros ($2.21 million) short of the funds it needed for its extra work in verifying that Iran is living up to its part of the six-month accord reached in November.

"The measures implemented by Iran, and the further commitments it has undertaken, represent a positive step forward, but much remains to be done to resolve all outstanding issues," he told a closed-door meeting of the IAEA's 35-nation Board of Governors, according to a copy of his speech.

Iran struck a deal with the United States, France, Russia, Germany, Britain and China on November 24 to curb its nuclear programme in exchange for some easing of sanctions, and it took effect on January 20.

The accord was designed to buy time for negotiations on a final settlement of the decade-old stand-off over nuclear activity that Iran says is peaceful but the West fears may be latently directed towards developing a nuclear bomb capability.

Those talks began in Vienna last month and are due to resume on March 17, also in the Austrian capital. The aim is to hammer out a long-term agreement by late July, though the deadline can be extended by six months if both sides agree. - Reuters