Syria accused Turkey of hostility and "lying" on Thursday after it intercepted a Syrian passenger plane en route from Moscow which Ankara said carried military equipment and ammunition for Damascus.

As Damascus accused Turkey's Prime Minister Recep Tayyip Erdogan of "lying," France warned of the risks posed by the rising tensions between the two neighbours.

"The Turkish prime minister continues to lie in order to justify his government's hostile attitude towards Syria," the Syrian foreign ministry said in a statement.

The information ministry challenged Erdogan to show the alleged weapons seized.

"The plane did not carry ammunition or military equipment and Erdogan's comments lack credibility and he must show the equipment and ammunition at least to his people," it said.

Erdogan earlier said the plane carried "equipment and ammunition shipped to the Syrian defence ministry" from a Russian military supplier.

On the ground, rebels fighting forces loyal to President Bashar al-Assad won more territory as they bid to secure a "buffer zone" in a swathe of land abutting the Turkish border, an AFP reporter said.

And in Damascus, a powerful blast rocked the military justice building, the Syrian Observatory for Human Rights reported, in what state television said was a terrorist attack.

UN-Arab League peace envoy Lakhdar Brahimi, meanwhile, held talks with officials in Saudi Arabia, which like Turkey has called for Assad to quit and supports the rebels.

Saudi deputy foreign minister Prince Abdul Aziz bin Abdullah urged Brahimi at talks in the Red Sea city of Jeddah on Thursday to work for "an immediate halt to the bloodshed of the Syrian people," the Saudi news agency SPA reported.

In the plane incident, Ankara scrambled two jets on Wednesday evening to force down the Syrian Air Airbus A-320, Turkish officials said, after receiving intelligence its cargo did not comply with civil aviation rules.

The aircraft with 35 passengers on board was grounded for nine hours before it was finally allowed to resume its journey to Damascus, as Turkey said it confiscated unspecified "objectionable" cargo.

Damascus said the interception was "hostile and reprehensible" and "another sign of the hostile policies of the Erdogan government, which harbours (rebels) and bombs Syrian territory."

It furiously demanded Turkey return the cargo it had seized at Ankara's Esenboga Airport.

"Turkish military aircraft... forced the plane to land without giving prior warning. The military aircraft were so close that there could have been an accident," said Syrian Air director Aida Abdel Latif.

Russia, a top Damascus ally and its biggest arms supplier, also said Ankara had put the passengers' lives at risk, and angrily denied it was carrying weapons or military equipment.

"We are concerned that this emergency situation put at risk the lives and safety of passengers, who included 17 Russian citizens," said Russia's foreign ministry.

Tensions have been high between Ankara and Damascus since the eruption of the conflict in March 2011 and were inflamed after a series of shell strikes from Syria on Turkish soil, including one attack that killed five civilians last week.

-- Rebels seek buffer zone --

Rebels are seeking to secure a buffer zone in the northwestern province of Idlib, and this week won control of the strategic town of Maaret al-Numan on the highway linking Damascus to second city Aleppo.

An AFP correspondent in the town said the insurgents had completely cut off the highway on Thursday, choking the flow of troops to battlefields in the north.

Fierce fighting raged on the periphery of Maaret al-Numan, where rebels have surrounded the key military bases of Wadi Daif and Hamdiyeh used by troops to bombard the town.

Firaz Abdel Hadi, a rebel spokesman, said almost 300 people had been killed in three days in Maaret al-Numan.

Other sources said regime forces executed around 65 prisoners before retreating, including one survivor who said guards had opened fire on 80 inmates before fleeing.

The floor of two cellars which held soldiers suspected of trying to defect or supporting the rebellion, were covered in blood and stained clothing, AFP witnessed.

Its nationwide toll for the day was at least 155 deaths -- 62 soldiers, 51 civilians and 42 rebels -- adding to its overall tally of more than 32,000 killed in the nearly 19-month conflict.

French President Hollande on Thursday warned of the situation between Turkey and Syria.

"It's a risk, and Turkey has been especially restrained," Hollande told French television and radio. "I welcome the attitude of its leaders because there have been aggressions and provocations."

In Damascus, a blast in the Mazzeh district of western Damascus targeted the military justice building which is near the ministry of higher education, the Syrian Observatory said.

State television said "a bomb exploded near the ministry of higher education" and that two people were wounded in the "terrorist attack."

The Syrian capital has been rocked by a string of bomb blasts, including suicide bombings, mostly targeting government buildings, since the March 2011 outbreak of an anti-regime revolt.