Syria's army said Thursday it would halt all military operations from midnight under a truce deal brokered by Russia and Turkey and supported by a leading Syrian opposition body.

The agreement was announced earlier by Russian President Vladimir Putin who said the Syrian regime and "main forces of the armed opposition" had signed on.

"The general command of the armed forces announces a complete halt to all hostilities on Syrian territory from the zero hour of December 30th," Syria's army said in a statement carried on state television.

It said that the ceasefire excluded the militant group and the former Al-Qaeda affiliate previously known as Al-Nusra Front, now rebranded the Fateh al-Sham Front.

The National Coalition, a leading Syrian political opposition group based in Turkey, confirmed its backing for the truce.

"The National Coalition expresses support for the agreement and urges all parties to abide by it," spokesman Ahmed Ramadan told AFP.

He said key rebel groups including the powerful Ahrar al-Sham and Army of Islam factions had signed the ceasefire deal, though there was no immediate confirmation from rebel representatives.

"The agreement includes a ceasefire in all areas held by the moderate opposition, or by the moderate opposition and elements from Fateh al-Sham, such as Idlib province," he told AFP.

Idlib, in northwest Syria, is controlled by an alliance of rebel groups led by Fateh al-Sham.

The group, in its previous incarnation as Al-Nusra, was designated a "terrorist" organisation by countries including the United States, as well as the United Nations.

The ceasefire agreement follows the recapture by Syria's government of the country's second city Aleppo from rebels, in the worst blow to opposition forces since the war began.

It will be the first nationwide halt in fighting since a week-long truce from September 12-19 that collapsed after several incidents of violence.

A previous truce was implemented in February. Both of those deals were organised by Russia and the United States.

The latest agreement is the first nationwide ceasefire brokered with the involvement of Turkey, a backer of the Syrian opposition.

Russia is a key supporter of Syria's President Bashar al-Assad and began a military intervention in support of his government in September 2015.

Despite backing opposing sides in the conflict, and a souring of relations after Turkey shot down a Russian warplane last year, Ankara and Moscow have worked increasingly closely on Syria.

They jointly brokered a ceasefire for Aleppo this month that allowed the last remaining rebels and civilians in the city's east to leave to opposition territory elsewhere.

More than 310,000 people have been killed in Syria since the conflict began in March 2011 with protests against Assad's government.

Successive bids to reach a peace deal to end the conflict have failed, but Moscow has said it is planning to convene new negotiations in Kazakhstan.

And the army statement said the ceasefire was intended to "create conditions to support the political track" in resolving the conflict.