DAMASCUS: The army took a pounding at the hands of rebels in northern Syria, a watchdog said on Friday, as tensions between Damascus and Ankara escalated over cargo seized from a Syrian passenger plane.

A rebel offensive killed more than 130 soldiers in two days, the Syrian Observatory for Human Rights said.

Forty-one soldiers were among at least 96 people killed nationwide on Friday, including 28 civilians, the watchdog said. On Thursday alone the army suffered 92 losses, its highest daily total in the 19-month conflict.

With an average of 20 deaths per day, the army has lost about 10,000 soldiers, with at least an equal number wounded, a military hospital official told AFP, updating a toll of 8,000 he gave in August.

As fighting raged on the ground, a war of words between Syria and Turkey grew angrier after Ankara said military supplies were aboard an airliner it intercepted en route from Moscow to Damascus.

And Turkey scrambled a fighter jet on Friday after a Syrian helicopter attacked the rebel-held town of Azmarin near the border, an official in Ankara told AFP.

The Syrian foreign ministry accused Turkish Prime Minister Recep Erdogan of lying when he said the jet intercepted on Wednesday was carrying “equipment and ammunition shipped to the Syrian defence ministry” from Russia.

Sergei Lavrov, Moscow's foreign minister, said the cargo was legal, in Russia's first remarks about the incident.

“This cargo is electrical technical equipment for radar stations, this is dual-purpose equipment but is not forbidden by any international conventions,”Lavrov said.

“There were no weapons on board this plane, nor could there have been,” he said in remarks posted on the Kremlin website.

Turkey's allies have warned of the risks embedded in the Syria conflict between the neighbours, which have exchanged cross-border fire amid fears the civil war could spark a regional conflagration.

Amid the growing alarm, German Foreign Minister Guido Westerwelle was due in Nato partner Turkey on Saturday for talks with his counterpart Ahmet Davutoglu.

“It is important that no one pours oil on the fire. We are counting on moderation and de-escalation,” said Westerwelle.