新一轮伊朗核问题谈判在维也纳举行

Iran and a group of six world powers continue their negotiations on Iran's nuclear program Wednesday, as they seek a longterm agreement to ensure it is peaceful in nature.

This round of talks in Vienna began Tuesday with what a spokesman for European Union foreign policy chief Catherine Ashton called "substantive and useful" discussions. The spokesman, Michael Mann, said he would not make any predictions about the outcome.

Iran and the group that includes the United States, Britain, China, France, Russia and Germany reached an interim deal last year for Iran to curb its most sensitive nuclear activity in exchange for limited sanctions relief.

As the talks go on, a large group of U.S. senators is calling for a set of "core principles" it wants to see in a permanent deal.