DAMASCUS: Syria is now in a full-scale civil war, UN peacekeeping chief Herve Ladsous said, as the United States accused Russia of supplying the regime of Bashar al-Assad with attack helicopters.

The UN peacekeeping chief told reporters that there was an escalation in violence in Syria as Assad’s forces seek to regain control of    “large chunks of territory” they had lost to the opposition.

Asked whether he believed Syria is in a civil war, he said: “Yes I think we can say that. I think there is a massive increase in the level of violence, so massive indeed that in a way it indicates some change of nature.”His comments marked the first time a UN official has openly spoken of civil war in Syria.

Meanwhile US Secretary of State Hillary Clinton accused Russia, a longstanding ally of Syria, of supplying Assad's regime with attack helicopters.

“We are concerned about the latest information we have that there are attack helicopters on the way from Russia to Syria, which will escalate the conflict quite dramatically,” Clinton told a think-tank discussion in Washington.

“They have from time to time said that we shouldn't worry, that everything they're shipping is unrelated to their actions internally. That's patently untrue,” the top US diplomat insisted.

She also warned that the UN mission in the strife-torn country may not survive once its three-month mandate expires in July. “If there is no discernible movement by then it would be very difficult to extend a mission that is increasingly dangerous for the observers on the ground,” Clinton told a forum in Washington.

World powers are groping to find a way to end 15 months of bloodshed in Syria with the toll growing daily despite a ceasefire that should have gone into effect from April 12. Violence killed 72 people on Tuesday alone, a watchdog said.

But Nato chief Anders Fogh Rasmussen said on Wednesday that military intervention like that carried out by the Western alliance in Libya last year was “not the right path”.

UN-Arab League envoy Kofi Annan has been trying to implement on the ground his six-point peace plan, which calls for both sides to lay down their arms immediately and participate in a Syrian-led political transition.

But there has been increasing violence as Assad has refused to step down and instead unleashed his heavily armed forces against the opposition.

The Britain-based Syrian Observatory for Human Rights says more than 14,100 people have now been killed in the uprising against the Assad regime.

With the Annan peace plan failing, the United Nations and the UN Security Council are studying “various options”, Ladsous said. A diplomatic flurry in recent days has seen a number of ideas put forward but the Nato chief said there were “no plans at this stage” for any operation by the alliance.

“A foreign military intervention is not the right path in Syria,” Rasmussen told reporters in Australia.

He hit out at Russia, though, for blocking tougher action by the UN Security Council saying it had a responsibility to wield its influence with Assad's government “and live up to (its) international obligations”.

“I strongly regret that the UN Security Council failed to reach an agreement on a legally binding resolution on Syria. I think that failure sends a very unfortunate, not to say dangerous, signal to the Assad regime,” he said.

Russian Foreign Minister Sergei Lavrov, whose government has been an outspoken opponent with China of Libyan-style regime change in Syria, was due in Tehran later on Wednesday for talks expected to touch on the conflict.

Russia has been pushing for an international conference to be joined by Iran, Syria's main Middle East ally, as well as other regional powers, an idea backed by Annan but criticised by Washington.

China expressed concern on Wednesday over the persistent violence. “We believe the situation in Syria is at a critical juncture,” foreign ministry spokesman Liu Weimin told journalists.

UN observers on Tuesday again reported they had come under fire as they tried to enter a town to check on the safety of hundreds of civilians reported trapped by fighting.

The UN Supervision Mission in Syria had been trying to reach the northwestern town of Al-Haffe, a Sunni Muslim enclave in a region mainly populated by members of Assad's Alawite minority, where troops have been besieging holed up rebel fighters.

A UN official, speaking on condition of anonymity, said the crowd that surrounded the UN convoy was carrying government flags and that at least 20 bullets hit the vehicles carrying the observers.

The almost 300 observers in the UN mission face a “grave security risk,”Ladsous said. UNSMIS is “a peacekeeping force when there is definitely no peace to observe.”