European Union foreign ministers on Monday agreed a slew of tough new financial and trade sanctions against Iran aimed at forcing a breakthrough in stalled talks on Teheran's contested nuclear program.

"This is a sign of our resolve," said British Foreign Secretary William Hague. "That we will step up the pressure, we will intensify the pressure and we will continue to do so over the coming months unless negotiations succeed."

The new sanctions mark one of the toughest pushes against Iran by Europe to date, and come amid mounting concerns over the Islamic Republic.