NEW YORK - In a major turnaround, Syria is pledging full cooperation with U.N. attempts to probe evidence that it secretly built a reactor that could have been used to make nuclear arms, according to a confidential document shared Sunday with the Associated Press.

If Syria fulfills its promise, the move will end three years of stonewalling. Since 2008, the International Atomic Energy Agency has tried to follow up on strong evidence that a target bombed in 2007 by Israeli warplanes was a nearly built nuclear reactor that would have produced plutonium.

The sudden readiness to cooperate seems to be an attempt to derail U.S.-led attempts to have Syria referred to the U.N. Security Council.

An IAEA report last week said the agency "assesses that the building destroyed . . . was a nuclear reactor." Washington and its allies had sought that finding in their push to have a 35-nation IAEA board meeting next month report Syria to the Security Council.

In the confidential note, sent Friday to board members, IAEA chief Yukiya Amano cited top Syrian nuclear agency officials as saying "we are ready to fully cooperate with the agency" on its probe of the suspect site.

But Washington is continuing its push. It has put forward a restricted draft of a resolution to be voted on at the IAEA meeting, beginning next Monday, that calls for reporting Syria to the Security Council for violating the Nuclear Nonproliferation Treaty.

The draft notes "with serious concern" Syria's refusal to allow IAEA inspectors follow-up visits to the bombed site after one they made in 2008. As a consequence, the board "decides to report . . . Syria's noncompliance with its NPT commitments," the document says.

Syria's maneuvering will complicate Western attempts to bring its nuclear secrecy to the attention of the Security Council. Still, Washington said it remained committed to trying.

"We are aware that the Syrian government has sent a letter to the IAEA regarding the agency's long-standing requests for full Syrian cooperation," a letter from the U.S. mission said. "Such cooperation would indeed be welcome but would not have any bearing on the finding of noncompliance."