Saudi Foreign Minister Adel Al-Jubeir has suggested that a ceasefire deal in Syria could be reached in the next 24 hours as the death toll continues to rise in the wartorn country.
These comments come despite the US and Russian presidents failing to reach an agreement on the sidelines of the G20 summit in China.
In February, a cessation of hostilities, brokered by US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov, was seen as a turning point in the Syrian conflict.
But seven months later, that deal has unravelled, despite attempts from both countries to stop the violence between Syrian government forces and rebel fighters.
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There was hope that US President Barack Obama and Russian President Vladimir Putin could reach a deal in Hangzhou during this week's G20 summit, but that has failed to eventuate.
President Obama said "gaps in trust" have made negotiations difficult.
Critics now believe a ceasefire is unlikely, but Saudi Arabia, a close US ally, argues there may still be hope.
Mr Adel Al-Jubeir has defended the negotiations during a visit to London, and suggested a deal may be brokered.
"I wouldn't describe it as a failure. I think that it's still a work in progress,” Mr Al-Jubeir said.
“There is a possibility of arriving at an understanding over the next 24 hours or so, and then we will test the seriousness of Bashar al-Assad and his allies, in terms of complying with a ceasefire like this."
A renewed cessation hinges on the US and Russia agreeing to closer military coordination against militant groups operating in Syria.
The US blamed Syrian President Bashar Al-Assad's government for violating the initial ceasefire and have called for him to eventually step down from his post.
A ceasefire deal brokered by Russia and the US in February has failed to hold. (AAP) Source: AAP
The US-backed coalition - including Saudi Arabia - have agreed with this stance, but Russia has been against it.
It all comes as the United Nations investigates further allegations that Syrian forces are using chemical weapons in their bombing raids.
Activists, opposition groups and local residents have claimed that chlorine gas and napalm are just some of the chemicals that have been used in numerous air assaults across Syria.
Vitit Muntarbhorn, from the UN's independent commission of inquiry on Syria, explained that a large number of those claims are coming from the city of Aleppo.
"Despite the glimmer of hope in February, there has been an evident militarisation since the end of March.”
The city is controlled in the east by rebels and in the west by the Syrian army.
"We've received reliable information concerning the use of chlorine gas in (the) Sheikh Maqsoud neighbourhood of Aleppo city, particularly at the beginning of April, on the 5th, with various people being taken to hospital for chlorine-gas inhalation symptoms,” Mr Muntarbhom said.
“We are also now investigating new allegations of chemical-weapons use."
Overnight, rebel fighters in Aleppo have accused government forces of executing another chlorine attack.
Each assault will be considered a war crime if the independent commission confirms the report.
The Syrian conflict five years on
More than a quarter of a million people have been killed and 11 million Syrians displaced since civil war ignited in Syria in 2011.
On Monday, six bombings by the self-proclaimed Islamic State killed more than 50 people across the country.
The deaths occurred in the coastal city of Tartus, as well as Homs, Hasakah and the capital Damascus.
Homs resident Muneer Hamadan told Chinese Central Television that a suicide bomber detonated himself at a checkpoint near the city's entrance.
"It was very loud. If there was no checkpoint, we would have had, in Homs, a day of devastation, and our hospitals would have cried tears of blood,” he said.
“This is the first time terrorists did not get to their target site in this region."
Meanwhile, Turkey said it believed the world powers have been non-committal about implementing the plan for a safe zone in Syria.
The UN commission's Mr Muntarbhorn lamented that the failure of the cessation pact has proved extremely deadly in the aftermath.
"Despite the glimmer of hope in February, there has been an evident militarisation since the end of March,” he said.
“That is a great shame and injustice, vis-à-vis the civilian population, innocent people, and that's why we are very much emphasising the need to get back to the negotiation table, restore and revitalise the cessation of hostilities, minimise civilian casualties and end indiscriminate attacks on the civilian population."
With Reuters
