US Secretary of State John Kerry was set to arrive in Geneva Sunday for renewed talks with his Iranian counterpart on Tehran’s nuclear program, after warning "significant gaps" remain ahead of a key deadline.

US Secretary of State John Kerry was set to arrive in Geneva Sunday for renewed talks with his Iranian counterpart on Tehran's nuclear program, after warning "significant gaps" remain ahead of a key deadline.

World powers are trying to strike a deal with Iran that would prevent Tehran from developing a nuclear bomb in return for an easing of international economic sanctions.

Kerry is set to arrive in the Swiss city Sunday morning for two days of talks with Iranian Foreign Minister Mohammad Javad Zarif, whose country denies its nuclear program has military objectives.

"There are still significant gaps, there is still a distance to travel," Kerry said in London on Saturday.

US and Iranian diplomats have been meeting in Geneva since Friday, and senior negotiators from the so-called P5+1 group of Britain, China, France, Russia, the United States and Germany were also expected to meet on Sunday to help drive the talks forward.