Diplomats say foreign ministers are preparing to join nuclear talks with Iran in an effort to meet a July 20 target date for a deal.
Two diplomats who are familiar with the closed talks said Thursday that U.S. Secretary of State John Kerry and his counterparts from Britain, France and Germany are tentatively scheduled to arrive in Vienna starting Saturday.
They said Russia's foreign minister and a senior Foreign Ministry official from China could also fly in.
Deep divisions persist over Iranian uranium enrichment, which can produce reactor fuel but also nuclear warhead cores. The U.S. wants deep cuts in the program; Iran demands that it be allowed to hugely expand it. The differences appear unbridgeable by July 20.
The diplomats demanded anonymity because their information is confidential.