The UN atomic watchdog voted Thursday to report Syria to the United Nations Security Council over allegations it built an undeclared nuclear reactor that was then destroyed by Israeli bombs, diplomats said.

At a closed-door meeting of the 35-member board of governors of the International Atomic Energy Agency, 17 countries voted in favour of a corresponding resolution by the United States and six against, diplomats attending the meeting said.

Azerbaijan, China, Ecuador, Pakistan, Russia and Venezuela all voted "no".

There were 11 abstentions, including Argentina, Brazil, Chile, India, South Africa and Peru, and one country -- Mongolia -- was absent from the vote, the diplomats said.

The IAEA will not officially publish the outcome of the vote given the confidential nature of the deliberations.

Washington and its Western allies had asked the IAEA's governing body to find Syria in "non-compliance" with its international obligations and report it to the Security Council in New York.

The last time the IAEA did so was in the case of Iran in February 2006.

Washington alleges that Syria was building an undeclared nuclear reactor at a remote desert site called Dair Alzour with North Korea's help until the site was bombed by Israeli planes in September 2007.

The IAEA began investigating the allegations in June 2008, but Syria has refused to cooperate all along and, with the exception of a one-off visit, has not allowed UN inspectors to Dair Alzour or related sites to verify the US claims.

Frustrated by Syria's three years of stonewalling, IAEA chief Yukiya Amano took the unprecedented step recently of stating his conviction that the site was "very likely" a covert nuclear reactor, as alleged.

Washington seized on Amano's assessment and tabled a resolution to censure Damascus at the regular June meeting of the IAEA board of governors this week.

"It is not appropriate behaviour for a country to build a secret nuclear reactor... without telling anyone and one that had no civilian purpose. That's why we had to do what we did today," US ambassador Glyn Davies told reporters after the vote.

"Syria's apparent attempt at constructing a covert, undeclared plutonium production reactor, a reactor with no credible peaceful purpose, represents one of the most serious safeguards violations possible," he said.

"Syria's nuclear intentions at Dair Alzour are clear; the reactor there was built for the express purpose of producing plutonium for possible use in nuclear weapons," Davies said, arguing a resolution was a "necessary and appropriate step" to safeguard the credibility of the IAEA and the international non-proliferation system.

However, in statements to fellow board members ahead of the vote, both Moscow and Beijing said they saw no reason for such action.

Russia and China are both veto-wielding permanent members of the 15-member Security Council.

"The UN Security Council is responsible for holding international peace and security and the site at Dair Alzour no longer exists and therefore poses no threat to international peace and security," the Russian statement said.

"We cannot therefore agree with the resolution and that is why, if it is put to a vote, we will vote against it," it said.

China followed simliar arguments, saying it saw "no reason to adopt the resolution or refer Syria to the Security Council."

Asked what Washington now expected from New York, US ambassador Davies said: "We'll have to see. Obviously this is not the end of the matter. We'll find in New York a separate dynamic, a separate debate and a separate conversation and a separate effort to air of the issues surrounding this matter."

Nevertheless, the US would "continue to seek to work with the Russians, the Chinese and all of the members of the Security Council when it comes time to consider this question in New York. Obviously there is still some work to do," Davies said.

Syria had been reeling from anti-government protests since mid-March, with human rights groups saying more than 1,100 people have been killed throughout the country.