The United Nations Security Council on Friday unanimously demanded that all parties to the civil war in Syria comply with the terms of a US-Russian deal on a "cessation of hostilities" due to take effect at midnight local time (2200 GMT).

The demand was included in a resolution drafted jointly by Russia and the United States that also urged the government and opposition to resume UN-brokered peace talks.

Before the 15-nation council voted, UN Syria mediator Staffan de Mistura told its members via video link from Geneva that he intends to reconvene peace talks on March 7 provided the halt in fighting largely holds and allows for greater delivery of humanitarian relief.

The council demanded "that all parties to whom the cessation of hostilities applies ... fulfil their commitments."

It also urged "all Member States, especially ISSG (International Syria Support Group) members, to use their influence with the parties to the cessation of hostilities to ensure fulfillment of those commitments and to support efforts to create conditions for a durable and lasting ceasefire."

De Mistura had abruptly aborted a first round of talks on Feb. 3 and urged countries in the International Syria Support Group, led by the United States and Russia, to do more preparatory work.

"It is going to be extremely challenging, especially at the outset, to make this work," US Ambassador to the United Nations Samantha Power told the council. "Even a partial de-escalation would make a real difference in the lives of Syrians."

She added that any violations of the cessation of hostilities must be met with a "sober, coordinated response."

Russian Deputy Foreign Minister Gennady Gatilov told the council that "we now have a real chance to end violence and to step up our collective combat against terrorism." He added that it would also be an opportunity to boost humanitarian aid relief.

Syrian Ambassador Bashar Ja'afari expressed the "readiness of the Syrian government to participate in every effort" to press ahead with a Syrian-led peace process.

The council meeting was delayed by half an hour as the United States and Russia engaged in last-minute negotiations on the text, diplomats told Reuters.

Among the changes was the removal of two references to the Saudi-backed High Negotiations Committee (HNC), a Syrian opposition coalition that Russia and Iran do not consider to be a legitimate representative in the peace talks.

British Ambassador Matthew Rycroft said the HNC references were "regrettably" removed.

Kurtis Cooper, spokesman for the US mission to the United Nations, said Washington had to accept the deletion in exchange for not including references to Russian-backed meetings on Syria that were held in Moscow and Cairo.

French Ambassador Francois Delattre was cautious.

"Resumption of (peace) discussions will only be possible if the agreed-upon commitments are strictly implemented by the regime and foreign powers that support it," he said,

He said he was disturbed by the "intensification of bombings by the Syrian army and Russia, a few hours only before the start of the (halt)."