Turkey said yesterday Syrian forces had fired towards a Turkish military transport plane involved in a search for an F-4 reconnaissance jet shot down by Syria last week, but the second aircraft was not brought down.

Damascus described its shooting down of the jet on Friday as an act of self-defence and warned Ankara and its NATO allies against any retaliation. Turkey said the incident would “not go unpunished” but it did not intend to go to war over it.

The disclosure of the second incident came on the eve of a NATO crisis meeting that Turkey summoned to address the shooting down of its F-4 jet, which Ankara has described as an unprovoked attack in international airspace.

In shell-shattered districts of Homs, heart of a 16-month-old revolt against President Bashar Al-Assad, rebels battled troops as aide workers tried to evacuate civilians.

Turkish television reported the desertion of a Syrian general and other officers across the border. Syria’s account of Friday’s shooting down, though tempered with commitment to a “neighbourly relationship”, seemed likely to further anger Ankara.

“NATO is supposed to be there to strengthen countries,” Syrian Foreign Ministry spokesman Jihad Makdissi told a Damascus news conference. “If their meeting is for hostile reasons (they should know that) Syrian land and waters are sacred.”

Turkey say the wreckage of the aircraft, shot down close to the Mediterranean maritime borders of both states, is lying in deep water. Makdissi said some flotsam had been found and turned over to Turkey. There was no word on the two airmen.

“The plane disappeared and then reappeared in Syrian airspace, flying at 100 metres altitude and about 1-2 km from the Syrian coast,” he said. “We had to react immediately, even if the plane was Syrian we would have shot it down.

The Syrian response was an act of defence of our sovereignty carried out by anti-aircraft machinegun which has a maximum range of 2.5 km.”

In Ankara, Turkish air force chiefs briefed both President Abdullah Gul, the commander of the armed forces, and the cabinet on what Prime Minister Tayyip Erdogan said would be a “decisive” response.

Turkey also said it would take the matter to the United Nations Security Council. Though not known for his emotional restraint, Erdogan has eschewed bellicose rhetoric over the incident, aware perhaps of Western reluctance to commit to any military action and wary himself of anything that could trigger a regional sectarian war.

According to Ankara’s account, the aircraft entered Syrian airspace briefly and by mistake while on a mission to test Turkish air defences. Some analysts have suggested it might in fact have been testing the responsiveness of Russian-supplied Syrian radar that would be a major obstacle to any foreign intervention, including supply of Syrian rebels or reconnaissance support.

“I’m not of the opinion that Turkey will immediately respond militarily,” agreed Beril Dedeoglu of Galatasaray University. “But if there is another action, then there will certainly be a military response, there is no doubt.”

Erdogan turned against former ally Assad after he refused his advice to bow to demands for reform. He now allows the rebel Free Syrian Army (FSA) to use Turkish territory as a safe haven, though Ankara denies supplying arms.

Over 30,000 refugees are also accommodated On Turkish soil. After Friday’s attack, Erdogan invoked an article in NATO’s founding treaty providing for urgent consultations if a member considers its security interests threatened.

Had he sought some kind of retaliation from the NATO meeting today, he could have invoked another article on mutual defence. That he did not, suggests the reaction will remain at least for now, on the diplomatic stage.

European Union foreign ministers meeting in Luxembourg called for a calm response from Turkey, saying they would increase pressure on Assad. “Military intervention in Syria is out of the question,” said Dutch foreign minister Uri Rosenthal. “It is not a matter of consideration for the Dutch government. That is also at stake in the … context of NATO.”

The International Committee of the Red Cross (ICRC) said it was again trying to arrange a safe evacuation of trapped civilians from Homs. But anti-government activists reported heavy shelling on central districts, including Jouret al-Shiyah and Al-Qarabis.

Video showed detonations and machinegun bursts from the skeletal shells of abandoned apartment blocks. The activist Syrian Observatory for Human Rights said Assad’s troops carried out raids and arrests in areas still under army control, and heavy fighting between government forces and rebel fighters was reported in the opposition centres of Idlib, Deir al-Zor and Deraa, the birthplace of the uprising. “In Deraa, regime regular troops are trying to reassert control of some villages with heavy shelling, gunfire and helicopters firing missiles,” the Observatory said in an email.

“People are fleeing villages because they know the army is trying to push out the rebels,” it said.

A Syrian general, two colonels, two majors, a lieutenant and their families – altogether 199 people – crossed the border into Turkey overnight, CNN Turk said. Thirteen Syrian generals are now in Turkey which is giving logistical support to the Free Syrian Army.

The new defections from Assad’s armed forces could encourage those awaiting a disintegration of Assad’s army. But there has been little indication of a broader trend to desertion in senior ranks, bound often to Assad by their Alawite background.

Alawites make up 90 percent of the officer corps. Such Sunni generals as there are tend to serve in administrative roles rather than field commands, their religious adherence making them in authorities’ eyes more likely to sympathise with Sunni rebels.

The United Nations has said more than 10,000 people have been killed by government forces, while Syria has said at least 2,600 members of the military and security forces have been killed by what it calls foreign-backed “Islamist terrorists”.

The intensification of the fighting has raised fears in Turkey of a flood of refugees and a slide into ethnic and religious warfare that could envelop the region. Ankara, like the West, is torn between a wish to remove Assad and the fear that any armed intervention could unleash uncontrollable forces.