Paris ? The U.N. Security Council’s five permanent members and Germany are expected to agree today on a new resolution to pressure Iran over its nuclear program, a French diplomat said. But a U.S. official said differences over the issue remain.

The senior French diplomat, who briefed reporters Monday on condition that he not be identified by name, said an agreement was very close and should be finalized by the six nation’s foreign ministers at a meeting in Berlin, Germany.

However, others were more cautious about what the talks could produce. Momentum for a third resolution has slowed since a U.S. intelligence assessment last month indicated Tehran had stopped active work on a nuclear weapons program in 2003.

A senior U.S. official said Monday that the six nations had made some progress in negotiating a new resolution in a flurry of weekend conference calls but that “substantial” differences still existed.