In a significant move, Iran agreed Sunday to provide additional information sought by the U.N. nuclear agency in its long-stalled investigation of suspicions that Tehran may have worked on nuclear weapons.

Iran insists that it never worked on — or wanted — such arms, and the International Atomic Energy Agency was proceeding with its inquiry with expectations that Tehran will continue to assert that all of the activities it is ready to reveal were meant for peaceful nuclear use.

Still, the IAEA’s announcement that Tehran was ready to “provide information and explanations” for experiments in a type of detonator that the agency says could be used to trigger a nuclear explosion appeared to be the latest indication that Iran’s new political leadership is seeking to ease tensions over its nuclear program.

The agency mentioned its concerns about detonator development three years ago on a list of activities it said could indicate that Tehran had secretly worked on nuclear weapons. The technology had “limited civilian and conventional military applications,” it said back then, adding: “Given their possible application in a nuclear explosive device . . . Iran’s development of such detonators and equipment is a matter of concern.”

Nuclear physicist Yousaf Butt welcomed the agreement as a “positive development.” At the same time, Butt, who often questions the methods and conclusions of the IAEA inquiry, said that such detonators are commonly used in oil extraction and related work. As such, he said, experiments with them should not be surprising in oil-rich Iran.

But David Albright, whose Institute for Science and International Security is often consulted by the U.S. government on proliferation issues, said the concession by Iran could “crack open the door” and lead to a resolution of the allegations that it worked clandestinely on atomic arms.

The detonator issue was not on top of the list in the 2011 IAEA report of possible nuclear weapons concerns, with the agency mentioning other suspected activities that it said appeared to have had no civilian applications.

As representatives from the IAEA and the Iranian government met over the weekend in Tehran, diplomats said Iran is ready to address agency questions about its suspected nuclear weapons work after years of dismissing the issue as based on fabricated U.S. and Israeli evidence.

But they also said that the process will get underway slowly. The fact that the Iranians are ready to engage on the detonator issue reflected caution by both sides after more than six years of stalemate on the investigation, with the agency focused on a step-by-step approach, starting with less sensitive issues and progressing to the arms-related queries.

The process began after the two sides reached an agreement three months ago that gave the agency access to several previously off-limits sites not directly linked to any suspected weapons activities. An IAEA statement Sunday said that Iran complied with the first steps of that deal and that both sides have signed off on “seven practical measures.”

— Associated Press