The clash over Iran's nuclear program is escalating, with U.S. sanctions and Europe's snapback threat putting Tehran under maximum pressure.

Iran has long insisted its program is peaceful, though it is the only non-nuclear-armed nation enriching uranium at that level. The U.S., the IAEA and others say Iran had a nuclear weapons program up until 2003.

The government in Tehran wants to continue talks with Germany, France and Britain next week in the dispute over Iran's nuclear programme. A meeting at the deputy foreign minister level is planned for Tuesday,