Hundreds of frightened Syrian evacuees from two besieged government-held towns were stuck at a rebel-held transit point on Thursday where dozens of their fellow townspeople were killed in a weekend bombing.

An international rights group on Thursday decried the use of land mines by Yemen's Shiite rebels in the impoverished Arab country at war, saying they have maimed hundreds of civilians and prevented many of the displaced from returning to their homes.

Human Rights Watch said in a new report that the rebels known as Houthis, who are allied with the forces of the country's former president, have used land-mines in at least six provinces since March 2015, when a Saudi-led coalition launched its military campaign against them.

A group of Yemeni protesters set out from rebel-held capital Sanaa Wednesday on a 225-kilometer (140-mile) march to call for unrestricted aid deliveries to the war-torn country. 

A Saudi military helicopter that crashed in Yemen killing 12 Saudi soldiers was likely hit by "friendly fire," military sources said Wednesday.

In a sign of the growing regional influence of Iran's Revolutionary Guards, a close adviser to its foreign operations commander began his new role as ambassador to Iraq on Wednesday, state media reported.

The United States wants to see a strong Saudi Arabia, U.S. Defense Secretary Jim Mattis said during talks Wednesday aimed at reinvigorating the Riyadh-Washington alliance.

The head of a global arms watchdog said Wednesday that "incontrovertible" test results from an alleged chemical strike in Syria showed sarin gas or a similar substance had been used.

Samples from 10 victims of the April 4 attack on Khan Sheikhun analyzed at four laboratories "indicate exposure to sarin or a sarin-like substance," said Ahmet Uzumcu, head of the Organization for the Prohibition of Chemical Weapons.

Palestinian leaders on Wednesday denounced Israel's refusal to negotiate with Palestinians on hunger strike in Israeli jails, warning of a "new intifada" if any of them die.

A bomb killed six people and wounded more than 30 in Syria's second city Aleppo on Wednesday, state television reported. 

The blast hit the southwestern neighbourhood of Salaheddin, which was once on the front line between rebels and government forces before the army retook full control of the city in December. 

Two strikes apparently carried out by US drones killed five suspected al-Qaida members in Yemen overnight, military sources said on Wednesday.