Military action against the Syrian regime would be a "tragic mistake", Russia said Sunday, warning the West not to preempt the results of a UN probe into alleged deadly chemical attacks.

Moscow warned there was a danger of history repeating itself a decade after the US-led invasion of Iraq, which it opposed, and urged the United States to refrain from any reckless decision.

"We strongly urge those who, by attempting to impose their own results on the UN experts, are raising the possibility of a military operation in Syria to use their common sense and refrain from committing a tragic mistake," foreign ministry spokesman Alexander Lukashevich said in a statement.

"All this is reminiscent of events from a decade ago, when the United States bypassed the UN and used fallacious information on the presence in Iraq of weapons of mass destruction to launch an adventure, the consequences of which are known to all," he said.

The United States and Britain led the military invasion of Iraq that toppled long-time dictator Saddam Hussein in 2003.

A UN mission had failed to find any of the weapons of mass destructions Saddam was suspected of possessing but the Iraqi strongman was known to have repeatedly used chemical weapons.

The United Nations said Sunday its inspectors in Syria could begin work as early as Monday, after Damascus agreed to the probe Sunday during a visit by top UN official Angela Kane.

Doctors Without Borders has said 355 people died last week of "neurotoxic" symptoms, after the opposition claimed regime forces unleashed chemicals east and southwest of Damascus last Wednesday causing more than 1,300 deaths.

The regime has denied the charges and in turn accused the rebels of using chemical arms.

Russia took credit for the deal allowing the UN inspectors to begin their work, saying it was the result of "relentless efforts" by Moscow with the Syrian regime.

"We are satisfied with the Syrian leadership's constructive approach towards ensuring an effective cooperation with the UN mission," the spokesman said.

Washington, which has said that evidence President Bashar al-Assad's regime used chemical weapons would cross a red line and warrant tougher action, said the Syrian offer was "too late to be credible".

Officials said US President Barack Obama, who held crisis talks Saturday with top aides, would make an "informed decision" about how to respond to an "indiscriminate" chemical weapons attack.

One official told AFP that based on the reported number of victims and their symptoms, and US and foreign intelligence, "there is very little doubt at this point that a chemical weapon was used by the Syrian regime against civilians in this incident."

Russia -- which together with Iran and China has supported Assad throughout the 29-month-old Syrian crisis -- urged the rebel camp to guarantee the safety of the UN team lead by professor Aake Sellstroem.

"It is important that the armed opposition controlling part of Eastern Ghouta ensure that the UN mission is able to operate safely and refrain from the kind of armed provocation witnessed against UN observers last summer," Lukashevich said.

Opposition leaders already said Friday that UN inspectors would have "unfettered" access to areas under rebel control such as Eastern Ghouta on the outskirts of Damascus to investigate the use of chemical weapons.

Jordan condemns chemical attacks in Syria
Amman (AFP) Aug 25, 2013 - Jordan on Sunday condemned chemical attacks in Syria, urging punishment for those responsible, days before it is due to host a meeting of Western and Muslim military commanders on Syria.

"We strongly condemn and denounce the horrible killings in Syria," Foreign Minister Nasser Judeh told a joint news conference with his Egyptian counterpart Nabil Fahmy.

"If (the attacks are) proven, those who have used chemical or any non-traditional weapons must be held accountable for such a criminal act," he said.

Syria's main opposition group, the National Coalition, accuses regime forces of killing more than 1,300 people Wednesday in chemical weapons attacks on the outskirts of Damascus.

The Syrian government denies the accusations and counters that the rebels used chemicals, including on Saturday on soldiers who tried to storm an insurgent neighbourhood in Damascus.

Jordan Prime Minister Abdullah Nsur, whose country is home to more than 500,00 Syrian refugees, said last week that the United States is providing Amman with technical assistance against any possible chemical threat from neighbouring Syria.

Judeh said on Sunday that Jordan "prepared plans two years ago to deal" with any possible the threat of chemical attacks from Syria.

Jordan is preparing to host a meeting in the coming days of top military commanders from the United States, Saudi Arabia, Qatar, Turkey, Britain, France, Germany, Italy and Canada to discuss the war in Syria.

A Jordanian official said on Saturday the meeting would be an opportunity to "examine the questions linked to the security of the region and the repercussions of the Syrian crisis, as well as means of military cooperation to assure the security of Jordan".

Judeh said the meeting "has been scheduled for months."

"The meeting is not a reaction to what happened recently in Syria. It is one of a series of meetings of the army chiefs of countries concerned about the situation in Syria," he added.

"At the same time, the meeting will discuss the situation and scenarios on the ground, especially after the recent dangerous developments. The army chiefs have to have comprehensive talks and examine the impact on the region."

Earlier Sunday, US Defence Secretary Chuck Hagel said the US military was ready to take action against Syrian President Bashar al-Assad's regime if ordered.