Unidentified assailants shot dead seven members of Syria's White Helmets rescue service early Saturday during a raid on their base in a jihadist-held northwestern town, the group said.

Ten Nobel laureates from across the world have penned an open letter urging Saudi authorities to hold off on the execution of 14 Shiites convicted of protest-linked crimes.

The death toll from Egypt's latest train disaster rose to 41 as cranes worked Saturday to clear the stricken railway line between Cairo and the Mediterranean city of Alexandria.

Yemen's blood bank has sent out an urgent appeal to anyone who will listen, as war and a blockade on the capital may force the centre to close within a week.

Four soldiers from the United Arab Emirates were killed when their helicopter crashed during a mission in Yemen, the UAE military confirmed on Saturday.

At least 23 rebel fighters were killed Friday and dozens more wounded in a suicide blast in southern Syria near the border with Jordan, a monitoring group said.

Two Arab Israelis were indicted Friday in a court in northern Israel for alleged contacts with the Islamic State jihadist group and illegal possession of weapons, the Shin Bet security agency said.

The UN Yemen envoy called on Friday for the urgent reopening of the airport in the rebel-held capital Sanaa, which has been closed to all but limited UN flights for a year.

A Saudi-led coalition supporting the government imposed an air and sea blockade on rebel-held territory in March 2015 and tightened it in August last year saying it was the only way to stop weapons smuggling.

Government bombardment killed three civilians on Thursday in a ceasefire zone near Syria's capital, a monitor said, in the second day of deadly shelling on the rebel area.

The Syrian Observatory for Human Rights and local residents also reported violations in a second "de-escalation zone" in the central province of Homs.

Israel is pushing ahead with a project to build a giant underground wall around the Gaza Strip to block tunnels that could be used for attacks, the army said on Thursday.