A Syrian clinic has been hit by an airstrike, the second time this week a medical facility has been struck, officials said.

The strike on the Al-Marja neighbourhood of rebel-held Aleppo wounded several people, the civil defence, known as the White Helmets, said.

Several other strikes appeared to target mosques in rebel-held areas. 

At least one child died and five people were injured in Friday's strikes, the Syrian Observatory for Human Rights said.

Earlier this week, 30 people, including two doctors, were killed when the Al-Quds hospital and nearby flats were hit in rebel-held Sukkari neighbourhood.

Overall, airstrikes on rebel-held areas of Aleppo have killed 123 civilians including 18 children during the past seven days, the Observatory said.

The strikes come as the UN called on the US and Russia to salvage the "barely alive" two-month truce.

Russian state media said the "regime of silence", agreed by Russia and the US, will apply for 24 hours in Damascus and Aleppo and 72 hours in Latakia.

The ceasefire brokered by the US and Russia in February has been crumbling, as casualty figures from government and opposition violence escalates.

Since mid-April more than 200 people are reported to have been killed, including at least 44 in an airstrike on a market in a rebel-held area of Idlib.

Airstrikes

The city's last paediatrician is reported to have been among those killed in the strikes on the Al-Quds hospital earlier this week.

The destroyed hospital was supported by the charity Médecins Sans Frontières. 

Muskilda Zancada, MSF head of mission in Syria, said the organisation "categorically condemns this outrageous targeting and destruction of yet another medical facility in Syria.

“This devastating attack has destroyed a vital hospital in Aleppo, and the main referral centre for paediatric care in the area. Where is the outrage among those with the power and obligation to stop this carnage?". 

Jane-Ann McKenna is the head of MSF in Ireland, and spoke to Newstalk Breakfast about the bombing.

She says it will take some time to determine the full death toll as it is 'chaotic on the ground', but said children were among those killed.

"The objective was very clearly to try to inflict the maximum amount of casualties among the civilian population," she explained.

UN Secretary-General Ban Ki-moon also condemned the bombing and "recent indiscriminate shelling by Government forces and opposition groups, as well as terrorist tactics by extremists.

"Attacks that target civilians are inexcusable violations of international human rights and humanitarian law. There must be accountability for these crimes," he added.

More than 270,000 people have been killed since the outbreak of the civil war in Syria in 2011.