The UN nuclear watchdog has decided to report Syria to the UN Security Council over its alleged covert nuclear programme, diplomats have said.
The board of the International Atomic Energy Agency (IAEA) voted to rebuke the country over claims it had built an undeclared nuclear reactor.
The alleged structure, which Syria has maintained was a non-nuclear military site, was destroyed by Israel in 2007.
The IAEA move comes as Syrian troops crack down on weeks of protests.
At the IAEA meeting at its headquarters in Vienna, 17 countries voted for and six against, including Russia and China.
Diplomats said that overall 11 countries of the 35-member board of governors abstained and one country was absent from the vote.
Israel bombed the desert site of the alleged reactor - near Deir Alzour in the country's remote north-east - in September 2007.
The IAEA began investigating the allegations in June 2008, but Syria has refused to co-operate and, with the exception of a one-off visit, has not allowed UN inspectors to Deir Alzour or related sites to verify the US claims.
Thursday's motion was proposed by the US and its Western allies who had asked the IAEA's governing body to find Syria in "non-compliance" with its international obligations.
According to AFP news agency, US Ambassador Glyn Davies told the closed-door assembly: "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 the intentions of the structure at Deir Alzour were clear and that a resolution was the only responsible course of action.
"The reactor there was built for the express purpose of producing plutonium for possible use in nuclear weapons."
Syria's ambassador to the IAEA called the agency's move "regrettable" but pledged that the country would honour its obligations.
"I think Syria has always been committed to its obligations and to its duties and I think we will continue to do so," Bassam Al-Sabbagh said after the meeting.
Syria is a signatory to the Nuclear Non-Proliferation Treaty (NPT), which gives it the right to enrich its own fuel for civil nuclear power, under inspection from the IAEA.
But it has also signed a safeguards agreement with the IAEA under which it is obliged to notify the UN's nuclear watchdog of any plans to construct a new nuclear facility.
The last country the IAEA referred to the Security Council was Iran, in February 2006.
The Security Council has the power to impose sanctions, a move it has taken in the case of Iran no less than four times.
However, diplomats are not convinced that this will happen in Syria's case due to opposition from both Russia and China.
The diplomatic move at the IAEA came a day after Britain, France, Germany and Portugal proposed a draft resolution condemning Syria's crackdown on protesters to the Security Council, despite the risk of a Russian veto.