France, US to pressure Iran on nuclear drive: Hollande

France and the United States warned Monday that they would up pressure on Iran over its nuclear programme -- which the West suspects is aimed at making an atomic bomb -- in upcoming talks with world powers.

"Despite all efforts, Iran is still refusing to be transparent," President Francois Hollande said at a press conference with US Vice President Joe Biden. "Therefore we will pressure it right to the end to ensure the negotiations succeed."

Iran on Sunday announced fresh talks with world powers on its nuclear drive and said it was open to an offer from the United States for two-way discussions if Washington's intention was "authentic".

Iranian Foreign Minister Ali Akbar Salehi said the six world powers planned to resume talks in Kazakhstan on February 25, and he insisted that Iran had never pulled back from the negotiations.

Iran and the United States, China, Russia, Britain, France and Germany held three rounds of talks last year aimed at easing the standoff over Iran's nuclear activities, which Tehran insists are peaceful.

The six called on Iran to roll back its programme but stopped short of meeting Tehran's demands that they scale back sanctions, and the last round ended in stalemate in June in Moscow.

Since then, talks have been held up over disagreements on their venue.