After a bruising meeting in a five-star Cairo hotel, Arab foreign ministers led by Gulf states hinted to Syrian President Bashar Al-Assad that unless he halts his violent crackdown, some Arab League members might arm his opponents.

The message was folded into Article 9 of a League resolution passed on Sunday that urges Arabs to "provide all kinds of political and material support" to the opposition, a phrase that includes the possibility of giving weapons to Assad's foes.

Diplomats at the meeting confirmed this interpretation.

Arabs are striving to unite the world around their drive to push Al-Assad to end the killing, but have gained little traction.

They had to scrap a floundering Arab monitoring mission to Syria. When they sought UN Security Council support for a transition plan under which Al-Assad would step aside, Russia and China vetoed the Western-backed UN draft resolution.

Moscow is an old ally of Syria and its top arms supplier.

Sunday's Arab League meeting raised the stakes. Its implicit shuffle towards backing military resistance to Al-Assad's forces was meant to add pressure on the Syrian leader and his Russian and Chinese allies. Yet it also risks leading to a Libya-style conflict or sectarian civil war that everyone wants to avoid.

"It is unacceptable for Al-Assad to practise all types of killing of civilians while we stand silent," one Arab ambassador said, explaining the rationale behind the resolution that returned the Syria issue to the United Nations with a call for a joint UN-Arab peacekeeping force.

"We will back the opposition financially and diplomatically in the beginning but if the killing by the regime continues, civilians must be helped to protect themselves. The resolution gives Arab states all options to protect the Syrian people," the envoy said.

"All options" is diplomatic language that leaves room for a military response. Two other diplomats spelled it out more explicitly, saying the resolution could allow arms transfers.

Salman Shaikh, director of the Brookings Doha Center, said the bloodshed was putting pressure on Arabs to act.

"The escalation is coming from the ground and it is coming from Assad himself. This is the reason they feel they cannot stand idly by just pursuing a diplomatic track," he said. "I suspect we will see a further militarisation of this conflict, with potentially quite widespread and dangerous consequences."

Smuggled guns are filtering into Syria but it is not clear if Arab or other governments are backing any such transfers.

Iraqi security officials say there are signs Sunni Muslim insurgents are beginning to cross the border to join Syrian rebels. Smugglers are cashing in as prices double for weapons reaching Syria concealed in commercial traffic.

For now, however, such weaponry cannot match the firepower that Al-Assad's military can bring to bear, analysts say, but that could change if Al-Assad fails to heed Arab peace calls.

A non-Gulf Arab ambassador said Qatar and Saudi Arabia had insisted on the "material support" wording to cover "all kinds of support, including weapons in future," adding: "But we see this as a dangerous escalation."

A senior Arab diplomat voiced fears that such a step could ignite a conflagration in Syria, a nation of Sunnis, Alawites, Christians, Kurds and Druze at the heart of the Arab world.

"It is a very sensitive situation in Syria. The door is open for a lot of possibilities," he said. "I think now Syria is at the beginning of a kind of civil war."

Syria's crisis has provoked a lop-sided rift among Arabs.

Sunni-ruled Gulf states, broadly driven by a desire to oust Al-Assad, an ally of their Shi'ite regional rival Iran, have the financial and political muscle to push through calls to isolate the Syrian leader. Wealthy Gulf countries, Bahrain apart, have also emerged with few scars from the wave of Arab uprisings.

Egypt, Algeria and Iraq, traditionally regional heavyweights with big populations and the largest armies, may have misgivings on Syria, but have limited clout for now. Algeria registered reservations about a joint UN-Arab force. Others kept quiet.

All three have challenges at home that blunt their ability to project their views. Iraq has its own sectarian divisions; Algeria has escaped a popular uprising, but remains wary; Egypt's generals may not like intervention in an Arab state but are preoccupied by street protests against military rule.

Lebanon, long dominated by its Syrian neighbour and its own Syrian- and Iranian-backed Shi'ite armed movement, Hezbollah, was the only League member formally to object to the resolution.

Highlighting the turmoil in the Arab world, Sunday's meeting in Cairo was shifted to the Marriott hotel across the Nile from the League's headquarters, located uncomfortably close to Tahrir Square, the focal point for Egyptian protesters.

Saudi Arabia's foreign minister, Prince Saud Al-Faisal, set the tone for the gathering in the plush surrounds of the former royal palace, making the case for backing the Syrian opposition.

In a speech before closed-door talks began, he told Arab ministers: "At our meeting today I call for decisive measures, after the failure of the half-solutions."

From then on, it was clear who was in charge, according to the non-Gulf envoy, who, like others, asked not to be named.

"These meetings were not open to discussion. The Gulf foreign ministers had positions and decisions they had reached earlier and they did not want to hear anything else," he said.

The six members of the Gulf Cooperation Council had met separately earlier in the day. One source said their line was backed by Morocco, Jordan and Tunisia, which will host a gathering of Arab and other "Friends of Syria" on 24 February.

An Arab source who attended the meetings described tetchy discussions on what kind of UN-Arab mission the League should request from the United Nations.

When a call for international "monitors" was proposed, Gulf ministers retorted that "what is happening in Syrian cannot be stopped without a peacekeeping force," the source said.

The meeting settled on requesting a "force."

The source said Qatari Prime Minister Sheikh Hamad bin Jassim Al-Thani, who was in the chair, also led calls for ending the Arab monitoring mission, which had been criticised by Syria's opposition since it began work in December and which has also faced internal dissent and logistical problems.

The monitoring team was duly scrapped in the resolution.

Yet prospects for securing UN Security Council backing for a joint peacekeeping force seem dim.

Arab League chief Nabil Elaraby floated the idea last week with the UN secretary-general. But it received only a lukewarm response from diplomats in New York, even though the United States and others said they would consider it.

"It really isn't realistic when there isn't a peace to keep ... This needs looking at as a future option rather than an option for now," said a Western diplomat at the United Nations.

The diplomat referred to the "unfortunate" precedent of the joint UN-African military force UNAMID sent to Sudan's Darfur region, which he said had lacked a clear command structure.

"I don't see the way forward in Syria as being Western boots on the ground in any form, including in any peacekeeping form. I think they would need to come from other countries, rather than Western nations," British Foreign Secretary William Hague said