TEHRAN, Iran (AP) — Senior U.N. investigators opened a new round of talks Wednesday with Iranian officials in Tehran in the hopes of restarting a probe into allegations that the Islamic Republic carried out atomic bomb trigger tests and other suspected weapons-related studies.

The semiofficial ISNA news agency reported that negotiations started at the headquarters of Iran's Atomic Energy Organization. It gave no further details.

The U.N. meetings are considered an important test of Iran's willingness to address Western concerns before the possible resumption of wider dialogue with the U.S. and other world powers. Negotiations with the six nations —the United States, Russia, China, Britain, France and Germany — fell apart more than six months ago and Iran has proposed getting them back on track, perhaps as soon as later this month.