BRUSSELS (Reuters) - World powers have asked Iran to hold a new round of talks over Tehran's nuclear work in February, a spokesman for the EU's foreign policy representative said on Monday.

The EU's Catherine Ashton, who oversees diplomatic contacts with Iran on its nuclear program on behalf of the United States, Russia, China, France, Britain and Germany, said last week the Iranian authorities were stalling on efforts to resume diplomacy over the program.

Her attempts to schedule new talks have failed since December, and a new date has been proposed.

"We have offered a date in February," spokesman Michael Mann told a regular news briefing in Brussels.

The six powers are concerned Iran is seeking to reach the capability to build nuclear weapons, but Tehran denies that.

(Reporting by Justyna Pawlak and Adrian Croft; editing by Rex Merrifield)