The head of the U.N. nuclear agency says Iran is cooperating “substantively” with a probe of suspicions that Tehran may have worked secretly on atomic arms.

But Yukiya Amano suggests that it is too early to make a judgment.

Iran recently submitted documents to Amano’s International Atomic Energy Agency for the first time, to back its claim that its tests with a special kind of detonator were meant only for civilian purposes. It denies any interest in nuclear arms.

But agency officials say they have other documentation indicating that the experiments were linked to research on setting off a nuclear charge.

Amano told the agency’s 35-nation board Monday that his experts are analyzing the information.

The detonator suspicions are only part of a wide range of alleged weapons-related experiments.

(AP)