Saudi Arabia on Tuesday renewed a warning to its citizens not to visit Yemen, still reeling from a year of political unrest and an ongoing war against al-Qaida, the state news agency SPA said.

"Given the instability and the security situation" in Yemen, "the (foreign) ministry is renewing its warning to all citizens not to travel" there "until the situation is stabilized," an official said in a statement carried by SPA.

Most of the victims of the massacre in the Syrian town of Houla were summarily executed, the U.N. rights body said on Tuesday, amid global outrage over the killings.

"It's believed that under 20 of the 108 killings can be attributed to artillery and tank fire," said Rupert Colville, spokesman for the United Nations High Commissioner for Human Rights.

At least 19 people were killed in violence on Tuesday in Syria, where clashes between regime troops and rebels raged, monitors said.

In central Homs province, seven civilians were killed overnight, the Syrian Observatory for Human Rights said. Three of them died when the army shelled the outskirts of restive Qusayr, while four died in the city of Homs.

Five people have been killed in an assault launched by al-Qaida fighters Tuesday on a Yemeni army convoy ferrying supplies to troops in the restive southern Abyan province, a military official said.

Three Yemeni soldiers and two fighters of al-Qaida were killed during the assault on the military convoy in the village of Mazraat Mashhour, southwest of Zinjibar, the capital of Abyan, the official told Agence France Presse on condition of anonymity.

Australia Tuesday expelled Syria's top diplomat over the "hideous and brutal" massacre at Houla of more than 100 people, with Foreign Minister Bob Carr saying he expected other countries to follow suit.

Syrian charge d'affaires Jawdat Ali was notified of the decision to expel him and one other diplomat a day after he was called in to meet with officials over the killings which sparked global condemnation.

U.N.-Arab League peace envoy Kofi Annan urged Syrian President Bashar Assad to "act now" to end 15 months of bloodshed, during a meeting in Damascus on Tuesday.

"I appealed to him for bold steps now -- not tomorrow, now -- to create momentum for the implementation of the plan," Annan told reporters in the Syrian capital.

Iran announced Tuesday it has delayed the launch of an experimental observation satellite that was supposed to have happened a week ago, saying it would now take place sometime within the next 10 months.

The country's space agency chief, Hamid Fazeli, announced the new window for launch to the official Islamic Republic News Agency (IRNA).

Britain summoned Syria's top diplomat in London to the foreign ministry on Monday to protest against the "sickening and evil" Houla massacre of more than 100 people, the government said.

Syria's charge d'affaires -- their ambassador has been withdrawn -- was warned during the meeting with a top Foreign Office diplomat that the international community would take further action if Damascus does not implement U.N.-Arab League envoy Kofi Annan's peace plan.

An Israeli court on Monday found two policemen guilty of negligent homicide after they dumped an injured Palestinian prisoner at the side of a West Bank road and left him to die, legal documents showed.

"By setting down the deceased in the condition and under the circumstances which they did, the accused breached their duty of care toward the deceased," Jerusalem magistrate Haim Liran wrote in his ruling, a copy of which was obtained by Agence France Presse.

The United Nations, not Syria, must investigate the Houla massacre, Human Rights Watch said adding that witness testimony suggest government forces were responsible for the carnage.

"Kofi Annan should push Syria's government to allow the U.N.-appointed Commission of Inquiry access into the country to investigate," the massacre in which at least 108 people were killed, including 49 children.