Thousands of displaced Syrian refugees are continuing to flock to the country's borders amid intensified bombing despite a temporary 'truce' agreement.

World powers agreed on Friday to a pause the fighting in Syria in a bid to resume peace talks and so that aid agencies could deliver essential food and supplies to besieged communities.

However, Russia pressed on with bombing in support of its ally, Syria's President Bashar al-Assad, who vowed to fight until he regained full control of the country.

More than 250,000 people have been killed and 13.5 million displaced in almost five years of fighting in Syria.

Although billed as a potential breakthrough, the "cessation of hostilities" agreement does not take effect for a week, at a time when Assad's government is poised to win its biggest victory of the war with the backing of Russian air power.

The temporary deal appeared to be the result of a compromise between the US, which had wanted an immediate ceasefire, and Russia, which had proposed one to start on March 1.

Although foreign ministers from the 17-member International Syria Support Group managed to seal an agreement to "accelerate and expand" deliveries of humanitarian aid to communities beginning this week, their failure to agree on a ceasefire leaves the most critical step to resuming peace talks unresolved.

Speaking for the support group, US secretary of state John Kerry hailed the result as a significant accomplishment but noted that a cessation of hostilities would only be a "pause" in fighting and that more work would be needed to turn it into a fully fledged ceasefire.

He also acknowledged that the agreements were "commitments on paper" only.

He said: "The real test is whether or not all the parties honour those commitments and implement them."

The halt will not apply to the battle against jihadist groups Islamic State, also known as Daesh, and al-Nusra Front.

Humanitarian access to the battle-scarred country is to be discussed by a working group in Geneva in a bid to relieve the suffering of millions of Syrians in the short term.

The US and Russia would co-chair the working group on humanitarian aid as well as a taskforce that will try to deal with the "modalities" of the temporary truce.

The taskforce will include members of the military along with representatives from countries that are supporting various armed groups in Syria.

The Syrian government and the opposition would both have to agree to the details.

It came as pressure mounted on Russia over civilian deaths in Syria, with France and the US urging greater caution.

French Prime Minister Manuel Valls and US Secretary of State John Kerry said civilians were dying in Russian air strikes.

One observers' group says at least 1015 civilians have been killed in Russian air strikes.

However, Russia has consistently denied hitting civilian targets and insists it is battling terrorists.

Russian Prime Minister Dmitry Medvedev said there was "no evidence of our bombing civilians, even though everyone is accusing us of this".

The UK-based Syrian Observatory for Human Rights said late last month that close to a quarter of those killed were under the age of 18.

The human rights group, which tracks the conflict, said yesterday that Syrian government forces were poised to advance into the Islamic State stronghold of Raqqa province as allied Russian jets kept up air strikes on rebel-held towns north of Aleppo.

At a security conference held in Munich yesterday, Kerry said: "To date, the vast majority of Russia's attacks have been against legitimate opposition groups.

"To adhere to the agreement it made, Russia's targeting must change."

He accused Russia of dropping so-called "dumb bombs" in Syria that do not have a precise target, saying this has led to the killing of civilians.

Last week, he said women and children were being killed "in large numbers" by Russian raids.

The differences between the stakeholders in a Syria settlement highlighted their lingering divisions despite Friday's "cessation of hostilities" agreement, which was not signed by any of the warring parties on the ground - government forces and the opposition.

Valls said his government "respects Russia and Russia's interests" but "that to re-discover the path to peace, to discussion, the Russian bombing of civilians has to stop".

Medvedev said Russia was "not trying to achieve some secret goals in Syria", adding that "we are trying to protect our national interests".

Meanwhile, Turkish Prime Minister Mevlut Cavusoglu has said Turkey and Saudi Arabia could launch ground operations against Islamic State in Syria.

He said Saudi Arabia was "ready to send both jets and troops" to Turkey's Incirlik air base.

Cavusoglu did not specify the number of troops or jets or the timing of a possible deployment, but said exploratory visits had been made.

The base is used by the US-led coalition in the campaign against Islamic State.