Delegates from more than 60 countries agreed in Tokyo Friday to ramp up pressure on Bashar al-Assad's regime and urged the international community to unite to force change in Syria.
The "Friends of Syria" condemned the "incessant killings, bombings of residential areas" and the "gross violation of human rights" that have taken place since Assad's forces moved to crush an uprising.
At a meeting in the Japanese capital, the group's fifth since its inception, they called for a full oil embargo on Syria, a move aimed at cutting off a rich source of currency for the regime.
In a statement released after the meeting, the group, which includes Western and Arab countries, called on "all members of the international community, especially members of the United Nations Security Council, to take swift, responsible and resolute action".
Two of the five permanent members of the Security Council -- China and Russia -- have blocked action.
The statement welcomed the formation of the National Coalition, a newly-unified opposition group that has been recognised by Britain, France and Spain as the legitimate representatives of Syria.
It also called for ramping up of sanctions to tighten the noose around the regime, insisting that any ill effects suffered by the populace were the fault of the government in Damascus.
"The group called on the international financial and business communities to diligently comply with ongoing and forthcoming measures against the Syrian regime," it said.
"The group reiterated its call on all states to impose an embargo on Syrian petroleum products and a ban on the provision of insurance and reinsurance for shipments of Syrian petroleum products."
Presently, the United States has banned the import of Syrian oil and gas, but the EU has not.
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Japanese Foreign Minister Koichiro Gemba earlier told the meeting the international community had to act together where the divided Security Council had failed.
"The violence has continued for more than 20 months and the number of casualties in Syria has surpassed 40,000 and counting today, causing a humanitarian crisis," he told representatives from 67 countries and organisations.
"We are gravely concerned about the spillover of the crisis to the entire region."
The Friends of Syria group has previously organised four such meetings -- in Paris in April, Washington in June, Doha in July and The Hague in September.
The group's next meeting will be in Bulgaria in February, the statement said Friday.
On Thursday US Secretary of State Hillary Clinton said Washington was weighing what further help it could give the Syrian opposition rebels.
"We are going to carefully consider what more we can do," Clinton told a Washington forum, saying the United States was constantly evaluating the situation and adding: "I'm sure we will do more in the weeks ahead."
But she stopped short of saying whether the US would recognise the National Coalition as the sole representative of the Syrian people.
Privately, US officials have said the Obama administration would likely go ahead and recognise the group at some point.
"We hope the National Coalition... will play a further role as an entity that represents a wider range of the Syrian society, with a common objective of having all the Syrians enjoy peace and prosperity in the new Syria," Gemba said on Friday.
Along with sanctions on the Assad regime, "providing assistance to refugees and internally displaced people" is essential, said Gemba, adding the world also had to "look ahead to a post-Assad" Syria.