A top Russian diplomat said on Thursday that the regime of President Bashar Assad is losing "more and more" control of Syria after 21 months of conflict and an opposition victory cannot be ruled out.

The comments by Deputy Foreign Minister Mikhail Bogdanov appear to be the first time a senior Russian official has explicitly acknowledged that the opposition could defeat Assad and take power in Syria.

Syrian Interior Minister Mohammed Ibrahim al-Shaar was wounded in a deadly bomb attack targeting his ministry on Wednesday but his condition is not serious, a security source told Agence France Presse.

"He was wounded in the shoulder when the ceiling fell in his office," the source said on Thursday, speaking on condition of anonymity.

At least 24 civilians, including a large number of children, were killed in two separate car bombings southwest of Damascus on Thursday, state media reported.

Eight people, mostly women and children, were killed by a car bomb in the poor Sunni town of Jdaidet Artuz, state television reported.

Israeli border guards shot dead on Wednesday a Palestinian teenager armed with a fake pistol in the West Bank city of Hebron, a police spokeswoman said, adding that clashes broke out after the shooting.

"A young Palestinian man approached a post manned by border guards. One of them asked him for his identity card. The Palestinian attacked him, brandishing a gun that he aimed at the head of the border guard," the spokeswoman said.

Four Libyan policemen were wounded on Wednesday when a bomb exploded in front of their station in the eastern city of Benghazi, security sources said.

"The blast coincided with a traffic police vehicle passing in front of Al-Fwihet station," police officer Adel Jibril told Agence France Presse.

The Syrian regime has begun using missiles and barrel bombs against opposition rebels in the past week or so, a top U.S. official said Wednesday, denouncing the increasing use of "vicious weapons."

Amid reports that Scud missiles have been fired, State Department spokeswoman Victoria Nuland said she "was not in a position to confirm types of missiles, simply to say that we're seeing missiles employed now."

An Omani appeals court upheld on Wednesday jail sentences ranging from six months to one year against 23 activists convicted for defaming the sultan and taking part in pro-reform protests last year.

The court in Muscat confirmed a one-year jail term against 11, including writers and bloggers and a young woman, accused of insulting the sultan and cyber crimes, ONA state news agency said.

Israeli border guards shot dead on Wednesday a Palestinian teenager armed with a pistol in the West Bank city of Hebron, sparking stone-throwing attacks on troops in the area, police and witnesses said.

"A Palestinian brandished a pistol as he approached a post of border guards, who opened fire and killed him," a police spokeswoman said.

The head of the Syrian National Coalition has been invited for talks in Washington following U.S. recognition of the opposition bloc as the legitimate representative of the Syrian people, a senior U.S. envoy said on Wednesday.

"We have extended an invitation to (Ahmed) Moaz al-Khatib and the Coalition leadership to visit Washington at the earliest opportunity," Deputy Secretary of State William Burns said in Morocco, where he was attending a meeting of the Friends of Syria group.

Unknown attackers fired at a convoy transporting United Nations personnel east of the Libyan capital on Wednesday, a U.N. spokeswoman told Agence France Presse, adding that no one was hurt.

"Yes, indeed there has been an incident. A U.N. convoy was shot at. There were no injuries," said Radia Achouri, confirming reports that the attack took place in Khoms, 100 kilometers (60 miles) east of Tripoli.