Israel's prison service caused the death of an Australian-Israeli known as "Prisoner X" by failing to prevent him from committing suicide in jail, a court document released on Thursday said.

Prisoner X, who was identified by Australian media as Mossad agent Ben Zygier, was found hanged in his isolation cell in Ayalon prison near Tel Aviv in December 2010 -- in a case which Israel went to extreme lengths to cover up.

Britain and its allies are "well prepared" to deal with the situation if Syrian President Bashar Assad's regime decides to use chemical weapons, a British minister said Thursday in Amman.

"We are extremely conscious of the threat of chemical weapons in Syria. The United Kingdom with partners are looking very carefully at how any particular incident might be dealt with," Foreign Office Minister for the Middle East Alistair Burt told a news conference.

A key witness in the trial of Israel's former foreign minister Avigdor Lieberman took the stand Thursday as his trial on charges of fraud and breach of trust began at Jerusalem Magistrate's Court.

At a first hearing on February 17, Lieberman pleaded not guilty to the charges in a trial which will decide the one-time nightclub bouncer's political future.

Iraqi Prime Minister Nuri al-Maliki warned on Thursday of a return to "sectarian civil war," with 176 people killed in three days of violence and troops surrounding a town held by gunmen.

Maliki urged ordinary Iraqis "to take the initiative, and not be silent about those who want to take the country back to sectarian civil war," in remarks broadcast on state television.

The departure of hundreds of young Europeans to fight in Syria poses "a serious threat" to Europe's security, the EU's anti-terror chief Gilles de Kerchove said Thursday.

EU citizens were heading "in the hundreds" to Syria which was drawing foreign fighters "in the thousands if we aggregate with those leaving from the Balkans and North Africa," he said.

U.S. Defense Secretary Chuck Hagel will meet United Arab Emirates leaders on Thursday to wrap up a major arms deal that both nations see as a way to thwart Iran's military power.

Hagel arrived in Abu Dhabi on Wednesday on the last leg of a six-nation tour of the Middle East in which he has sought to renew ties with American allies who share Washington's concerns over Iran's nuclear project and Syria's civil war.

Iraq's army deployed reinforcements around Sulaiman Bek and was preparing Thursday to move into the northern town, a day after it was seized by a group of gunmen, official sources said.

Also Thursday, a spokesman for now-dispersed protesters near the town of Hawijah in northern Iraq, where the latest wave of violence began on Tuesday, vowed to seek revenge for a "massacre" at the protest site, where clashes killed 53 people.

Syria's air force carried out air strikes on rebel enclaves near Damascus on Thursday, while clashes pitted rebels against troops in the north of the capital, a monitoring group said.

Warplanes also struck villages in the northwestern province of Idlib, rebel-controlled Raqa in the north, Hasake in the northeast and Daraa in the south, said the Syrian Observatory for Human Rights.

Authorities in Bahrain, which has been hit by Shiite-led protests for two years, have voiced "dismay" over an assessment by the U.S. State Department of the rights situation in the kingdom.

"The report includes texts which are totally far from the truth, adopting a manner that fuels terror and terrorists targeting Bahrain's national security," state news agency BNA late on Wednesday quoted government spokeswoman Samira Rajab as saying.

Former U.S. president George W. Bush says he remains "comfortable" with the decision to invade Iraq, even as a new spate of bloody violence hit the country and rocked politics in Baghdad.

Bush told ABC News in an interview marking the opening of his presidential library on Thursday that it was up to history to judge the invasion of Iraq in 2003, prompted by fears of weapons of mass destruction that were never found.