An Israeli man carries gas mask kits with his son as he leaves a distribution point in Jerusalem on Wednesday. Fearing that the fallout of a possible US strike on Syria could spill across their northern border and drag the Jewish state into the conflict, Israelis scurried to replace their old gas masks. Photo: AFP

A senior US official said on Wednesday that any military action against Syria would not be unilateral and the US is conferring with its allies on possible strikes that are likely to extend beyond a day.

Chinese observers said a large-scale US strike is unlikely, as the US does not want another war in the Middle East, and Syria's allies, such as Russia, will not stand by.

"Any military action would not be unilateral. It would include international partners," the senior administration official told reporters on condition of anonymity, adding that "options are not limited just to one day."

As the possibility of Western military intervention against the Syrian regime is growing, US officials declined to comment on whether the potential military action would go beyond the use of cruise missiles and require fighter aircraft to enter the airspace of Syria, reported AFP.

The official also said that US President Barack Obama's deputies were discussing with Turkey, Jordan and other partners on possible measures they could take in case of any retaliation by the Syrian government if military action was launched.

Meanwhile, British Prime Minister David Cameron said that Britain would submit a draft resolution "condemning the chemical weapons attack by Assad" to the UN Security Council on Wednesday.

However, the prospect of an imminent strike looks dim as an emergency session will be held by the French parliament to debate the Syria conflict on September 4.

Shi Yinhong, director of the Center of American Studies at the Renmin University of China, told the Global Times that it is very unlikely that the US would launch large-scale military action against the Syrian regime.

"The US would not want to get mired in yet another war in the Middle East, especially when the Syrian regime is much more powerful than former Iraqi leader Saddam Hussein's regime and former Libyan leader Muammar Gaddafi's regime," he said.

However, Shi said that Washington and its allies would be very willing to take the chemical weapons attack as an opportunity to weaken the Syrian regime.

Syria's Prime Minister Wael al-Halqi said Wednesday that Syria would surprise the "aggressors" in case of a US-led military action.

Yin Gang, a research fellow of Western Asian and African studies under the Chinese Academy of Social Sciences, told the Global Times that large-scale military intervention by Washington and its allies could result in a regional war as Iran and Russia are unlikely to stand by if the military intervention seriously threatened the Syrian regime.

Russia said on Wednesday that it was premature to mull any response by the UN Security Council before findings are released by the UN team investigating an alleged chemical weapons attack in Syria.

Also on Wednesday, Lakhdar Brahimi, the UN-Arab League envoy to Syria, said it was clear that chemical "substances" had been used in last week's chemical weapons attack in Syria, which was thought to have killed hundreds of people.

But UN Secretary-General Ban Ki-moon said UN inspectors still needed four days to conclude a probe into chemical weapons use in Syria.

Amid speculation of possible strikes, Iranian Supreme Leader Ayatollah Ali Khamenei warned Wednesday that any US military intervention against its ally Syria would be a "disaster" for the region.

"The region is like a gunpowder depot. (Its) future cannot be predicted" in case of a military strike against Syria, he said.

"China resolutely opposes the use of chemical weapons no matter who uses them," Foreign Minister Wang Yi said on Monday, adding that China supports an independent and objective investigation by the UN inspectors, and a political resolution should be the only way to resolve the Syrian crisis.

The Chinese embassy in Syria said that since there are merely 10-20 Chinese citizens in Syria, except for embassy staffers and media workers, there would not be a mass evacuation of Chinese nationals, people.com.cn reported on Wednesday.

Agencies contributed to this story