Western and Arab nations stepped up verbal pressure on Syrian President Bashar al-Assad on Sunday, mistrusting his acceptance of a plan to end a year of bloodshed, but stopped short of arming rebels or fully recognising an opposition council.

In a sign of impatience with what they see as stalling by Assad, the 'Friends of Syria' urged peace envoy Kofi Annan to set a timeline for next steps, including a return to the U.N. Security Council, if the Syrian leader fails to halt bloodshed.

Violence has raged on unabated despite Annan's mediation.

The Syrian Observatory for Human Rights reported at least 41 people killed across Syria on Sunday, including five in bombardment of pro-opposition districts in Homs.

In a final communique, the 83-nation group said Assad did not have an open-ended opportunity to meet his commitments to Annan, who is acting for the United Nations and Arab League.

"The regime will be judged by its deeds rather than its promises," the communique said. Security Council members China and Russia and Syria's ally Iran were among countries that stayed away from the conference in Istanbul.

Assad has accepted, but not yet implemented, Annan's six-point peace plan, which calls for the military to cease fire, withdraw from towns and cities, and allow humanitarian access.

"We will not let the Syrian regime misuse another opportunity, which is the last chance for the situation in Syria," Turkish Foreign Minister Ahmet Davutoglu told a news conference after the meeting he hosted.

The 'Friends of Syria' recognised the opposition Syrian National Council (SNC) as a legitimate representative of all Syrians, and "noted" it as the main opposition interlocutor with the international community - wording that fell short of full recognition of a group hampered by chronic disunity.

The group made no mention of supporting or arming the rebel Free Syrian Army (FSA), as advocated by some Gulf Arab states, but said it would "continue to work on additional appropriate measures with a view to the protection of the Syrian people".

Aid for rebels

Hardline Gulf states are likely to interpret the phrase as a licence to fund, if not arm, the FSA, while the United States and others will see it as allowing supplies of non-lethal equipment to the loosely organised armed opposition to Assad.

U.S. Secretary of State Hillary Clinton told the conference her government was supplying "communications equipment that will help activists organise, evade attacks by the regime and connect to the outside world" and was "discussing with our international partners how best to expand this support".

Clinton berated Assad for not acting on Annan's peace plan. "Nearly a week has gone by, and we have to conclude that the regime is adding to its long list of broken promises," she said.

"There is no more time for excuses or delays ... This is a moment of truth," Clinton told a news conference later.

Western powers have been wary of military intervention in Syria, but Davutoglu sounded an alarm bell, comparing the situation there to the plight of Bosnia in the 1990s.

"In the case of Bosnia, the international community was too slow ... therefore we lost many people," he said. "In the case of Syria ... we have to act without delay."

Chris Phillips, a Middle East expert at the University of London, said the Istanbul meeting had produced little.

"It's another damp squib from the international community, reflecting the fact that their hands are tied," he said, citing divisions over arming the rebels between the West and Arab League hawks such as Qatar and Saudi Arabia.

"They have a very limited amount of leverage that they can place on the Assad regime," Phillips said, noting that the group's endorsement of Annan's plan had effectively dropped previous Arab and Western demands for Assad's removal.

Western and Arab sanctions on Syria have failed so far to soften the government's crackdown on its opponents.

SNC leader Burhan Ghalioun pressed the "Friends of Syria" to strengthen the rebel army and open humanitarian aid corridors.

He chided foreign powers and the Arab League for failing to reach a political agreement against Assad. "For this reason the Syrian regime has carried out more massacres and has been encouraged by this, but enough is enough," Ghalioun declared.

In a separate statement, the SNC requested communications and other non-lethal equipment for the FSA, and possibly arms.

"The provision of arms is not our preferred option. We know it carries high risks of escalation into civil war but we cannot stand back and watch our people being massacred," it said.

No respite from violence

The "Friends of Syria" urged Syrians, especially those serving in the military, security agencies and government, "not to be a part of the atrocities committed by the regime".

The group called for international action to deny arms supplies to Damascus, and demanded humanitarian access, with daily two-hour pauses in fighting to allow aid to be delivered.

Syrian media derided the Istanbul meeting, which the Baath newspaper described as "a regional and international scramble to find ways of killing more Syrians and destroying their society and country, to reach the broad goal of weakening Syria".

Around 50 Assad supporters protested outside the conference centre, waving Syrian, Russian and Chinese flags and brandishing pictures of the Syrian leader. "Allah, Syria, Bashar, that's it" and "Down, down USA" they chanted, before police removed them.

Annan will brief the U.N. Security Council on Monday on his efforts to calm a conflict in which Syrian security forces have killed more than 9,000 people, by a U.N. estimate, while rebels have killed 3,000 troops and police, according to Damascus.

His six-point plan demands that Assad order his military to cease fire, withdraw troops from cities and open daily windows for humanitarian aid, but does not require him to step down.

The rebel FSA said on Saturday it would stop shooting if Assad pulled heavy weaponry out of urban areas, but Damascus said its forces must stay to maintain security.

If Annan's plan falters, the next steps could include a return to the Security Council for a binding resolution, with increased pressure on Assad's allies Russia and China, which have endorsed Annan's mission, to get tough with Damascus.

If the former U.N. chief signals progress, Council diplomats say work could start on a resolution to send 200 to 250 unarmed U.N. observers to Syria to monitor an eventual ceasefire