The Astana process by Russia, Iran and Turkey to end the Syrian conflict has only led to a "stalemate" in efforts to establish a constitutional committee crucial to a political settlement, the US said on Thursday.

Establishment and convening of the committee by year's end "is vital to a lasting de-escalation and a political solution to the conflict," State Department spokeswoman Heather Nauert said in a statement.

Her comments came after the outgoing United Nations envoy to Syria, Staffan de Mistura, regretted that there was "no tangible progress" on the composition of the constitutional committee at two days of talks which ended Thursday in the Kazakh capital Astana.

Moscow and Tehran, allies of the Damascus regime, began the Astana process in January 2017 along with rebel-backer Turkey.

The Astana process followed a Russian military intervention which tipped the military balance in favor of Syrian President Bashar al-Assad's authoritarian regime.

"Russia and Iran continue to use the process to mask the Assad regime's refusal to engage in the political process" under UN auspices, Nauert said.

She added that "success is not possible without the international community holding Damascus fully accountable for the lack of progress in resolving the conflict."

The Astana process has gradually eclipsed the earlier UN-sponsored negotiations framework known as the Geneva process, which had put more emphasis on political transition but failed to curb violence that has killed more than 360,000 people and displaced millions.

Syria's war began in March 2011 as an uprising against Assad but morphed into a complex conflict with myriad armed groups, many of whom are foreign-backed.

Lebanon army 'detains several hundred Syrians' in raids on camps
Beirut (AFP) Nov 29, 2018 –

Lebanon's army has detained around 400 Syrians in raids on refugee camps in the eastern Bekaa valley, mostly for overstaying their residence permits, a military source said Thursday.

Almost eight years into Syria's war, neighbouring Lebanon hosts around 1.5 million Syrians, many of whom live in the east of the tiny Mediterranean country.

On Wednesday, the army in the Arsal area detained "33 people with arrest warrants, 56 people without identity papers, and 300 others over expired documents", it said in a statement.

The military source said all were Syrians, and that those with no or out-of-date documents had been handed over to the security forces.

Those arrested had "committed an action against the law", they told AFP, without providing any further details.

Lebanon's army from time to time sweeps down on Syrian refugee camps, especially those in the east of the country.

Tens of thousands of Syrians live there, many from towns and villages on the other side of the Syrian-Lebanese border.

Arsal mayor Basel al-Hojeiri said that some of those who had been detained on Wednesday were then released overnight, complaining that the way in which the raids were carried out was "not right".

"They come to arrest a certain number of wanted people, and end up detaining 400," he said.

"They detain this huge number to then determine which ones are wanted among them, when it would be much better if they directly arrested those they wanted without bothering everybody else," Hojeiri said.

Last year, the army detained dozens of Syrians in mass raids on camps in Arsal, sparking a controversy after it announced four of them had died in custody.

Images circulated on social media showed dozens of bare-chested men lying down on the ground under the scorching sun with their hands tied.

Rights organisations demanded an investigation into the cause of their deaths.

Many Syrians live in tough conditions in Lebanon, and depend on international aid organisations for their survival.

Since the start of the year, around 8,000 Syrians have gone home from Lebanon, according to an AFP tally of official figures.

Lebanese security forces however claim tens of thousands have taken part in these returns, which are coordinated between Beirut and Damascus.

They waive late fines for those whose residency papers have expired if they agree to return to Syria.

The Syrian conflict has killed more than 360,000 people and forced millions from their homes since it started with the brutal repression of anti-government protests in 2011.