Syrian troops backed by helicopter gunships clashed with rebels near a barracks in Aleppo on Friday as battles broke out around a military airport elsewhere in the northern province, monitors said.

In Damascus, state news agency SANA said the army unearthed the bodies of 25 people shot execution-style in the Qadam district and blamed "armed terrorist groups," the regime's term for rebels.

President Bashar Assad has hit out at Saudi Arabia, Turkey and Qatar, accusing them of arming Syrian rebels but insisting they will not win, according to excerpts from an interview to appear in an Egyptian newspaper on Friday.

"They suddenly saw money in their hands after a long period of poverty and think they can buy history and play a regional role," Assad told al-Ahram al-Arabi, which put excerpts from the interview on its website on Thursday.

Shelling by Syrian government forces trying to win back a border post seized by rebels left two Turkish civilians wounded Thursday, a Turkish official told AFP.

They were injured by four fragments of a shell that exploded just on the Syrian side of the border, the official said on condition of anonymity, adding that another unexploded shell was found and the area sealed off while it was detonated.

At least 30 civilians were killed and dozens more wounded Thursday in an explosion at a petrol station in northeastern Syria, a human rights group said, with activists saying it was an air strike.

"At least 30 people were killed and 83 were injured, although unconfirmed sources say the number of dead was actually more than 50," the director of the Syrian Observatory for Human Rights, Rami Abdel Rahman, told AFP.

Last Thursday, on 13 September 2012, the U.S. Department of the Treasury imposed sanctions against Mustafa Badreddine, designating him pursuant to Executive Order 13224 “for providing support to Hizbullah’s terrorist activities in the Middle East and around the world,” said the Defense counsel at the Special Tribunal for Lebanon in a statement on Thursday.

The Defense for Mustafa Amine Badreddine considers that these sanctions amount to political interference with the ongoing judicial process before the Special Tribunal for Lebanon.

Diplomats from over 60 nations and the Arab League met in The Hague on Thursday to toughen and improve coordination of sanctions against the regime of Syrian President Bashar Assad.

"We need vigorous implementation," Netherlands Foreign Minister Uri Rosenthal told the opening of the "Friends of Syria" sanctions working group.

More than 29,000 people have been killed in violence in Syria since an anti-government uprising broke out in March last year meeting with a bloody crackdown, a human rights group said on Thursday.

"As of Wednesday (September 19), at least 20,755 civilians, 1,148 defectors and 7,095 soldiers had been killed across Syria since the outbreak of the revolt," Syrian Observatory for Human Rights director Rami Abdel Rahman told Agence France Presse.

Rebel fighters shot down a helicopter in a battleground town near Damascus on Thursday, a watchdog said, as Syria's opposition declared parts of the capital a "disaster area."

A series of explosions rocked the town of Douma, just northeast of Damascus, shortly before the rebels downed the helicopter, said the Syrian Observatory for Human Rights.

U.N. leader Ban Ki-moon said Wednesday that President Bashar Assad and the Syrian opposition were determined to fight to the end, but renewed appeals for political dialogue.

Ban told a press conference it was "troubling" that 18 months into the uprising against Assad there was no solution in sight.

Syrian rebels seized control of a border crossing on the Turkish frontier on Wednesday after clashes with troops loyal to President Bashar Assad, a Turkish official told Agence France Presse.

Turkish media footage showed Syrian rebels pulling down the Syrian flag at the Tall al-Abyad border post on the main highway between the city of Raqa in northeastern Syria and the Turkish city of Sanliurfa.