The U.S. and Iran are making last-minute progress at nuclear talks but will need to extend negotiations to next month, Western diplomats said Monday, Nov 24, according to the Associated Press.

Their comments matched earlier word that negotiations had now turned two-track, with the sides still racing to reduce differences at the negotiating table but also working on how long to extend the talks beyond the Monday midnight deadline.

A Western diplomat spoke of "progress made this weekend," adding that the talks would reconvene in December, with the venue yet to be decided.

U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif agreed Sunday to start discussion on continuing the talks past the target date.

But Chinese Foreign Minister Wang Yi said Monday negotiators were still having "consultations" on a final agreement that meets both U.S. demands for strict curbs on Tehran's nuclear program and Iran's push for sanctions relief, also suggesting that moves toward an immediate deal had not yet been abandoned.

International negotiators are worried that Iran is using its nuclear development program as a cover for developing nuclear weapons, and they have imposed economic sanctions on Tehran. Iran denies that, saying it is only interested in producing power.

Wang arrived Monday, joining the foreign ministers of the other countries negotiating with Iran — the U.S., Russia, Britain, France and Germany, in a top-level diplomatic effort to push the talks forward.