Updated February 07, 2018 10:14:00

Syrian and Russian airstrikes on a besieged rebel-held area near Damascus have killed at least 55 people, one day after 30 people were reported killed in similar attacks.

Syrian government and allied Russian forces have been pounding the eastern Ghouta suburbs of the capital for two days.

First responders known as the White Helmets say 55 people were killed on Tuesday, while the Syrian Observatory for Human Rights put the death toll at 70.

Russia has waged a punishing aerial campaign against Syria's armed opposition since intervening in the civil war on the side of its ally, President Bashar Assad, in 2015.

Eastern Ghouta, home to about 400,000 people, is also reeling under a government siege that has prevented aid from getting in.

Photo: The UN is calling for a ceasefire so it can provide aid to civilians in the area. (Reuters: Bassam Khabieh)

The United Nations has called for an immediate humanitarian ceasefire.

"They are calling for at least [a] one-month humanitarian pause starting immediately throughout Syria given the very critical humanitarian needs, and the inability to provide the aid that we do have," UN spokesman Jens Laerke said.

The UN said it had a plan to reach 700,000 people with relief in the next two months, if it can get the permission to proceed.

Meanwhile, the lead investigator of a UN-mandated Commission of Inquiry on Syria said his team was looking into reports that bombs allegedly containing weaponised chlorine were used against civilians on two recent occasions, in the rebel held towns of Saraqeb, in Idlib, and Douma, in Eastern Ghouta.

In a statement Paulo Pinheiro said the spiralling violence in Syria had made "a mockery of the so-called 'de-escalation zones'" — an agreement last year between Russia, Iran, and Turkey to stabilise the lines of conflict and open corridors for urgently needed humanitarian relief.

He described the government's siege and indiscriminate bombardment of eastern Ghouta as "international crimes".

Eastern Ghouta resident Nour Adam, who spoke to the ABC last month about the "hellish" conditions in the area, said the most recent airstrikes have hit the civilian population hard.

"Since the early morning we have had so many airstrikes and shells and missiles on the towns of eastern Ghouta," he said.

"So many women and children were killed…yesterday there was 33 martyrs too.

"A member of the civilian defence died when he was saving people under the rubble in Arbeen."

Photo: Civil defence members and civilians run from an air raid in eastern Ghouta. (Reuters: Bassam Khabieh)

ABC/AP

Topics: unrest-conflict-and-war, syrian-arab-republic

First posted February 07, 2018 09:10:12