VIENNA: The United States accused Syria on Friday of using the "brutal repression" of its people waging an uprising as an excuse not to address U.N. nuclear watchdog concerns about suspected past illicit nuclear activity in the Arab state.

For its part, Syria insisted at a debate of the governing board of the International Atomic Energy Agency that it had agreed last year with the IAEA on how to handle the issue. This was denied on Monday by the IAEA chief in a speech to the board.

The IAEA has long sought access to a site in Syria's desert Deir al-Zor region that U.S. intelligence reports say was a nascent, North Korean-designed reactor designed to produce plutonium for nuclear weapons before Israel bombed it in 2007.

The Vienna-based watchdog has also been requesting information about three other sites that may have been linked to Deir al-Zor.

IAEA chief Yukiya Amano said earlier this yeart Syria had asked for understanding of its "delicate situation" in response to requests for Syrian cooperation with his inspectors' inquiry.

President Bashar Assad is fighting a 17-month-old revolt in which more than 27,000 people have been killed.

U.S. IAEA envoy Robert Wood said Syria's "own destabilizing actions are no justification for its refusal" to abide by its commitments under the nuclear Non-Proliferation Treaty (NPT), set up to prevent the spread of atomic weaponry.

"The Assad regime is using its brutal repression of the Syrian people as an excuse for not cooperating with the agency's investigation," he told the closed-door board governors' session, according to a copy of his speech.

Syria says Deir al-Zor was a conventional military facility but the IAEA concluded in May 2011 that it was "very likely" to have been a reactor that should have been declared to its anti-proliferation inspectors.

"Syria must allow access to all relevant locations, materials and persons, including in particular the three additional sites suspected of having a functional relationship to the clandestine Deir al-Zor," Wood said.

Syrian Ambassador Bassam Al-Sabbagh repeated his country's position that Deir al-Zor was not a nuclear reactor and said an agreement had been reached with senior IAEA officials last October on an action plan on how to clarify the matter.

According to one diplomat present, Al-Sabbagh told the board that if Syria could convince the IAEA that Deir al-Zor was a non-nuclear facility then the issue of the three other sites was "moot".

Amano, the IAEA director-general, did not respond at Friday's board session, but on Monday he told the opening day of the week-long board meeting: "I wish to make clear that no agreement was ever reached on a so-called action plan."

The veteran Japanese diplomat later told a news conference that "some options" had been discussed during the IAEA team's visit to Damascus last year but that they were rejected after a careful review by the IAEA.

"It was not sufficient because the so-called action plan is limited only to the Deir al-Zor site and Syria was not ready to discuss other locations," Amano said.

The Non-Aligned Movement (NAM) of mostly developing states said in a statement read out by Iranian Ambassador Ali Asghar Soltanieh that it welcomed "Syria's resolve to continue cooperating" with the IAEA.