Russian President Vladimir Putin on Wednesday indicated that Russia will not rule out backing US-led military action in Syria if solid proof is given that the Syrian government used chemical weapons, but he also warned that the use of force without UN approval would be an "aggression."

As the US and its allies prepare to bypass any Russian UN veto and attack Damascus, there is little chance of Putin's support. But his words may herald new efforts to overcome great power rivalries that have let Syria descend into bloody chaos, Reuters said.

Putin made the remarks in an interview with Russian media ahead of the G20 summit starting Thursday in St Petersburg.

Gao Zugui, a research fellow with the China Institute of Contemporary International Relations, told the Global Times that Putin softened his tone over Syria so as to allow for unpredictable circumstances, but that does not mean Russia has fundamentally changed its stance.

"Putin has never said Russia backs the Assad regime in any case," he noted. "What Russia really cares about are its own interests in Syria."

Gao predicts that it would be unlikely for Russia to take part in any military action against Syria even if there were convincing evidence showing the Syrian regime was behind the chemical weapons attack.

However, he said Russia would very likely choose not to stop the military action in that case, in an effort to improve its relations with the US.

Commenting on Putin's Wednesday remarks, Chinese Foreign Ministry spokesman Hong Lei said China supports an independent investigation by the UN, and no preconditions or conclusions should be made prior to the release of the results.

Although no official meeting between Putin and Obama has been planned at the G20 summit, a White House official said Wednesday that two leaders are expected "to have an opportunity to speak on the margins of the various meetings of the G20."

After British lawmakers voted against any military action against Syria, France has vowed to back US-led strikes. The French parliament was set to hold a debate over the issue Wednesday.

Before taking part in the G20 summit, Obama arrived in Sweden on Wednesday to meet with the Swedish Prime Minister Fredrik Reinfeldt over the Syrian crisis.

"(The prime minister) and I are in an agreement that in the face of such barbarism the international community cannot be silent," Obama said after the meeting.

The visit came after Obama has secured backing from key figures in the US Congress for his bid to launch military strikes against Syria.

The US Senate Foreign Relations committee on Monday drafted a bipartisan measure that would impose a time limit of 90 days for any US military action. The measure would also impose a ban on deployment of any US ground troops in Syria.

Ni Feng, a research fellow on American studies at the Chinese Academy of Social Sciences, told the Global Times that the odds of US Congress approving a military intervention are increasing with the support of the US Senate Foreign Relations committee and two leading Republicans in the House of Representatives.

"The attitude of the Senate committee, which has a big say in the Senate on foreign affairs, will have a big influence over other Senators in the upcoming Congress vote over Syria," he said, adding that the House of Representatives, where the Republicans are the majority, is also very likely to back the military action as they have long been criticizing Obama's hesitation over Syria.

A diplomat from the Chinese embassy in Syria told the Global Times Wednesday, on condition of anonymity, that six Chinese citizens in Syria will leave Syria before the US Congress votes on Syria on September 9. The diplomat also said, except for the embassy staff, there were 26 Chinese citizens in Syria on Wednesday.

Agencies contributed to this story