The UN Security Council on Tuesday failed to agree on a joint declaration on war-torn Syria, capping a day of negotiations in which the organisation's special envoy to the country called to jump-start the deadlocked peace process.
Russia, Syria's main ally, repeatedly blocked negotiations on the matter, diplomats said.
The conflict in Syria, which broke out after the regime suppression of anti-government protests in 2011, has killed more than 380,000 people and displaced millions.
Endless rounds of UN-backed peace talks in the decade since failed to stem the bloodshed and in recent years were largely overtaken by parallel negotiations led by Russia and Turkey.
"The divisions in the international community need to be bridged," Geir Pedersen, the UN special envoy for Syria, said after a Security Council videoconference.
Mr Pedersen said that without "constructive international diplomacy" on Syria, it was unlikely that "any track – constitutional track or any other – will really move forward".
Diplomats said the failure to agree on a declaration was down to Russia, which had made demands unacceptable to western nations.
"The Russians are asking too much," a diplomat said.
The council's monthly meeting on Syria is usually public, but officials kept the session private after a meeting of the Syrian Constitutional Committee in Geneva last month ended with no progress.
Estonia's UN envoy Sven Jurgenson lamented the lack of progress.
"The aim was not to create a debating club, but to give Syrian people a way out from a 10-year conflict," he said.
"It is clear to everyone that the Syrian government has taken advantage of these meetings to delay any real reconciliation."
The committee was created in 2019 to modify Syria's 2012 constitution, which directs the organisation of elections under UN supervision.
"Session five of the Constitutional Committee was a missed opportunity and disappointment," Mr Pedersen said of the January meeting, which included the Syrian regime, the opposition and civilian society.
"There is a lack of trust and confidence and a lack of will to compromise – and a lack of political space to compromise too," he said.
Diplomats said western powers were unanimous at Tuesday's meeting in decrying the failure of the political process.
One representative said the constitutional committee had achieved nothing, and accused the Syrian regime for "delay tactics".