Israeli guards supposedly keeping a round-the-clock watch on a mystery dual nationality prisoner held in isolation failed to notice his suicide for a full hour, a newspaper reported on Thursday.

Although his cell was fitted with four CCTV cameras, the guards did not see Ben Zygier, identified by media as an Australian-Israeli Mossad agent, remove a sheet from his bed and take it with him into the shower cubicle.

Israeli settlers on Thursday torched six cars in the northern West Bank village of Qusra, Palestinian security sources alleged.

They told Agence France Presse that attackers set fire to the vehicles in the early hours and residents of the village, near the city of Nablus, saw them driving to the nearby settlement outpost of Esh Kodesh.

A powerful car bomb exploded Thursday close to ruling party offices in Damascus, killing over 50 people and causing widespread destruction in the Syrian capital's deadliest attack for more than nine months.

The bombing, which rocked the city centre and sent thick smoke scudding across the skyline, was followed soon after by a mortar attack on a nearby military headquarters.

Yemeni police shot dead four people in Aden on Thursday in clashes with protesters calling for southern independence on the first anniversary of the ouster of autocratic leader Ali Abdullah Saleh, their movement said.

The police fired on the protesters after thousands of them had gathered at a square in the southern port city, Fathi Ben Lazraq, a member of the Southern Movement, told Agence France Presse.

Iraqi officials said Thursday that gunmen have attacked an army checkpoint north of Baghdad, killing four soldiers and wounding four others.

Police officials said gunmen in two cars sprayed the checkpoint with bullets in the town of in Duluiayah. The town is about 75 kilometers north of the Iraqi capital.

International Syria peace envoy Lakhdar Brahimi has agreed to extend his mission for at least six months, diplomats said Wednesday.

Brahimi's first six-month contract with the United Nations and Arab League, in place of Kofi Annan, ends on Friday.

Saudi Arabia on Wednesday beheaded by the sword a Pakistani man convicted of drug trafficking, the interior ministry said.

Aqeel Khan Mohammed Riyad was convicted of attempting to smuggle heroin into the ultra-conservative Muslim kingdom, the ministry said in a statement carried by state news agency SPA.

British Foreign Secretary William Hague discussed Syria's bloody conflict on Wednesday with Qatar's crown prince during a visit to the gas-rich Gulf country, the official QNA news agency reported.

Qatar's Crown Prince Tamim bin Hamad al-Thani met with Hague in Doha, where they "discussed cooperation between their countries as well as regional developments, mainly in Syria," said QNA.

Tunisia was in political limbo on Wednesday as President Moncef Marzouki suffered setbacks in his bid to replace Prime Minister Hamadi Jebali, who quit after failing in his plan to form a non-partisan cabinet.

Talks between Marzouki and Rached Ghannouchi, head of Islamist Ennahda party, ended inconclusively, dashing hopes of a soon end to Tunisia's deepest political crisis since the revolt that ousted Zine El Abidine Ben Ali two years ago.

A member of Oman's consultative council voiced concern Wednesday for the health of 30 jailed activists who have been on hunger strike for the past 12 days, as activists said some of them were in hospital.

"We are concerned, as are their families, about the deterioration of the health conditions of the detainees after 12 days on hunger strike," said Malek al-Abri, a member of Oman's elected Majlis al-Shura (consultative council).