Air strikes by the Syrian regime and its ally Russia Saturday killed 12 civilians in the country's last major opposition bastion where a rise in violence has forced tens of thousands to flee.

It took medics and residents of Qatabah in southern Yemen more than 12 hours to retrieve the bodies of the Al-Halimi family from under the rubble of their collapsed home.

Clashes erupted in southern Yemen on Friday after an explosive device targeted separatist militants, a security source said.

Air strikes on Syria's northwestern Idlib region stopped on Friday after the government announced it had agreed to a truce following more than three months of deadly bombardment.

A US air strike killed at least eight policeman in Afghanistan's Helmand province, a government official said on Friday, the latest casualties from a rise in air and ground operations against the Afghan Taliban.

A air strike by the Saudi-led coalition against a radio station in Yemen's Houthi-held port city of Hodeidah killed four people on Sunday, residents and medical sources said.

The bombing on a crowded market in rebel-held northern Yemen killed a total of 51 people, according to the Red Cross.

Fifty-six children were also among the 79 people wounded in the Thursday strike on Saada province, a rebel stronghold that borders Saudi Arabia.

At least 29 children were among those killed in the air raid on Thursday on a bus in a crowded market in Dahyan, Saada province, according to the International Committee of the Red Cross.

The coalition said it had carried out what it called "legitimate military action" in the area targeting Houthi rebels.

Yemeni government forces backed by a Saudi-led coalition have been conducting an offensive to capture Hodeida from Iran-backed Houthi rebels.

Hamas sources said the casualties were security men working at an observation post near Rafah, in the southern Gaza Strip.