The diplomatic crisis between Syria and Turkey continued to escalate yesterday (Sunday) as the two countries banned each other from using their airspace, even for civilian flights.
The tit-for-tat move comes after Turkey last week forced down a passenger plane and confiscated a cargo of Russian radar equipment intended for President Bashar al-Assad's regime.
Ahmet Davutoglu, the Turkish foreign minister, accused the Syrian government of "abusing" civilian flights by transporting military equipment.
Syria responded by announcing the closure of its own airspace, in "accordance with the principle of reciprocity", the SANA state-run news agency said.
Human Rights Watch accused the Syrian air force of increasing its use of cluster bombs in the past week as the regime fought to regain control of the country.
The weapon, which has been banned by most nations, was allegedly thrown from planes and helicopters in an attempt to regain control of the strategically crucial town of Maarat al-Numan, which is on the main Aleppo-Damascus highway and which fell to the rebels last week.
Cluster munitions drop hundreds of bomblets across a wide area, designed to kill and maim as many people as possible. The bomblets remain live if they do not detonate on first impact, and can kill and maim years after they are deployed. Human rights groups say their use near civilian homes can be a war crime.
"Syria's disregard for its civilian population is all too evident in its air campaign, which now apparently includes dropping these deadly cluster bombs into populated areas," said Steve Goose, arms director at Human Rights Watch.
Footage from towns near Damascus, Homs, Aleppo and Latakia also showed evidence that cluster bombs had been used.
The videos even showed children and adults handling the bomblets.
More than 100 nations have banned their use under a convention that became international law in 2010 - but Syria has not signed it, and nor have Russia, China or America.
The cluster bombs were deployed as rebels made a renewed push to seize more territory close to the Turkish border. Activists said several hundred soldiers became trapped when rebel fighters laid siege to a military base in the town of Urum al-Sughra, on the main road between Aleppo and Turkey.
"Rebels attacked an armoured column sent from Aleppo to rescue the 46th Regiment at Urum al-Sughra and stopped it in its tracks," said Firas Fuleifel, one of the activists.
In another reported victory for the opposition, rebels claimed to have shot down a Syrian fighter jet on Saturday night. Video footage posted on YouTube showed large metal parts, some on fire, scattered on the ground, surrounded by a cheering crowd.
A source supplying weapons to certain rebel brigades told The Daily Telegraph that a small number of surface-to-air missiles had found their way into rebel hands.
Eleven Syrian soldiers were captured by Turkish troops as they tried to cross into Turkish territory to flee the fighting yesterday, according to a Turkish newspaper.
Turkey has reportedly bolstered its defences by deploying 250 tanks and 55 jets along its southern border.
"We will hit back without hesitation if we believe Turkey's national security is in danger," said Davutoglu.