More than 19,000 people have been killed in violence in Syria since the outbreak of an anti-regime revolt last year, the Syrian Observatory for Human Rights said on Sunday.

"At least 19,106 people, most of them civilians, have been killed since March last year," the Observatory's Rami Abdel Rahman told Agence France Presse.

Feared forces headed by President Bashar Assad's brother used helicopters Sunday in a new offensive against rebels in Damascus, as clashes also raged in Syria's second city Aleppo, activists said.

The Fourth Brigade headed by Maher Assad was leading the assault in the Damascus neighborhood of Barzeh, triggering an exodus of residents, said the Syrian Observatory for Human Rights.

A car bomb in the center of the Iraqi city of Najaf wounded 23 people on Sunday, security and medical officials said, a relatively rare attack in the Shiite holy city.

The 7:00 am (04:00 GMT) attack struck near a restaurant in Najaf's old town, provincial health department spokesman Salim Naama said. Of the 23 wounded, four were seriously hurt, he said.

Attackers on Sunday blew up a gas pipeline in Egypt's Sinai used to export fuel to Israel and Jordan, the 15th such attack since 2011, the official MENA news agency reported.

Witnesses told Agence France Presse they heard a loud explosion and saw flames from the site of the explosion near the northern Sinai town of El-Arish.

Dozens of Turkish truck drivers on Saturday accused Free Syrian Army rebels of having burned and looted their lorries as they captured a border post in Syria from government troops.

A group of truck owners, traders and transporters who have braved Syria's highways despite the bloody conflict have been waiting since Friday at Turkey's Cilvegozu border crossing, opposite Syria's Bab al-Hawa post.

Prime Minister Najib Razak said Malaysia will immediately evacuate its nationals from strife-torn Syria and shut its mission there in response to the worsening security situation.

Foreign Minister Anifah Aman had sought Najib's approval to evacuate Malaysians as violence escalated across Syria.

Syrian rebels controlled on Saturday one of the three main border crossings between Iraq and Syria despite shelling from President Bashar Assad's forces, Iraqi officials told AFP.

The officials also said Syrian refugees had attempted to enter Iraq but Baghdad had ordered its security forces not to allow them to cross into the country from any entry points.

U.N. chief Ban Ki-moon said Saturday that Syrian authorities have "manifestly failed" to protect civilians and called on the international community to act to stop the violence.

"The Syrian government has manifestly failed to protect civilians and the international community has a collective responsibility to live up to the U.N. charter and act on its principles," Ban said during a visit to Croatia's Brijuni Island as part of a week-long Balkans tour.

An Egyptian court on Saturday sentenced Ali Wanis, a Muslim cleric and ex-lawmaker, to 18 months in prison after he was found guilty of committing an "indecent act" in a car with a female university student.

Wanis, however, can avoid jail by paying 1,500 Egyptian pounds ($250) in bail as the case goes to an appeal court.

The Palestinian Islamist group Hamas ruling Gaza said on Saturday it would free more than 150 prisoners "as a gift" for the holy month of Ramadan.

The Hamas government "was releasing 159 inmates ... on the occasion of the holy month of Ramadan and as a gift" from its head, Ismail Haniya, a statement quoted interior ministry official Islam Shahwan as saying.