Diplomats have been trying to get the Iranians to return to negotiations on its nuclear program.
Ambassador Mark Lyall Grant said senior diplomats from the six nations — the U.S., Russia, China, Britain, France and Germany — held a conference call Wednesday on a proposal for a fourth round of sanctions, which the United States circulated in January.
China has not responded to the proposal. But Lyall Grant said that during Wednesday's call, "my understanding is that they have agreed to engage substantively."
