The European Union has banned new purchases of Iranian oil and frozen the assets of Iran's central bank as part of a Western campaign to pressure Tehran to suspend controversial parts of its nuclear program.

EU foreign ministers agreed to the new sanctions Monday in Brussels. Their decision allows member nations with existing contracts for Iranian oil to honor those purchases until July 1. The grace period is meant to help major buyers such as Greece, Spain and Italy find alternative sources of supply before the full ban takes effect.

Western powers accuse Iran of trying to develop nuclear weapons under cover of a civilian energy program, a charge Tehran denies.

The leaders of France, Germany and Britain urged Iran's leaders “immediately to suspend its sensitive nuclear activities,” saying they will “not accept Iran acquiring a nuclear weapon.” In Washington, U.S. President Barack Obama said the new sanctions demonstrate once more the international community's resolve to address “the serious threat presented by Iran's nuclear program.”

Read the full story at Voice of America.

Update: Iran slams EU oil embargo, warns could hit U.S.