Syria insisted on Monday that a Turkish warplane shot down by its forces violated its airspace as NATO members prepared to hold an emergency meeting at Ankara's request to discuss the downing of the jet.
The incident has reignited concern over the Syria conflict, with the European Union condemning the Damascus regime and slapping new sanctions against it while also warning of the dangers of military escalation.
As tensions simmered, a Syrian general was among a new group of officers and soldiers to defect and join the growing rebel ranks in Turkey, media reports said.
On the ground, 41 people were reported killed nationwide, amid opposition claims the regime was preparing for a new "massacre" in the besieged flashpoint city of Homs.
The Red Cross said booby traps and the lack of a clear agreement from troops and rebels were blocking its efforts to evacuate the sick and wounded from Homs.
NATO member states are to hold a crucial meeting on Tuesday to discuss Friday's downing of the Turkish jet, as Ankara and Damascus traded blame for what happened.
Turkey says the F-4 Phantom was fired on over international waters, not inside Syrian airspace as Damascus maintains, and is urging ministers to honour the collective defence rights of a fellow NATO member.
Syrian foreign ministry spokesman Jihad al-Makdissi told a news conference the plane had violated Syrian airspace.
"The Turkish warplane violated Syrian airspace, and in turn Syrian air defences fired back and the plane crashed inside Syrian territorial waters.
"What happened is a gross violation of Syrian sovereignty.
"If the goal of the (NATO) meeting is to calm the situation and promote stability, we wish it success," Makdissi said.
But "if the goal of the meeting is aggression, we say that Syrian airspace, territory and waters are sacred for the Syrian army, just as Turkish airspace, territory and waters are sacred for the Turkish army."
Turkey has called Tuesday's emergency NATO meeting, invoking Article Four of the alliance's founding treaty which covers threats to members' security.
Foreign Minister Ahmet Davutoglu told Turkey's TRT television that when it was shot down, the jet was in international airspace, 13 nautical miles from Syria, and that Syria gave no warning before opening fire.
The fighter had been on an unarmed training mission, and both crew are still missing.
"Nobody should dare put Turkey's (military) capabilities to the test," Davutoglu said.
'De-escalation is now decisive'
The downing of the Turkish jet triggered a chorus of international condemnation as well as appeals for restraint to prevent a military escalation of the Syria conflict which is now in its 16th month.
EU foreign ministers meeting in Luxembourg rounded against Syria, imposing new sanctions targeting government ministries and companies, including a bank and a television channel.
But on the eve of the NATO meeting, many also cautioned against military intervention.
In a joint statement condemning the incident, the ministers praised Turkey's "measured and responsible initial reaction," and said the matter needed to be investigated "thoroughly and urgently."
It was "important that all forces understand that de-escalation is now decisive," German Foreign Minister Guido Westerwelle said.
NATO members Britain, France and the United States have all condemned Syria, with Britain saying Damascus should not be allowed to act with impunity.
French Foreign Minister Laurent Fabius called the shooting down "completely unacceptable," while US Secretary of State Hillary Clinton condemned a "brazen and unacceptable act" and promised US assistance in the investigation.
A Turkish diplomat told AFP that one Syrian general, two colonels and five other army officers including two majors, accompanied by 24 family members, crossed into Turkey late on Sunday.
Turkey's Anatolia news agency had initially put the number at 33 defectors -- the general, two colonels and 30 soldiers.
The latest defections brought to 13 the number of generals seeking refuge in the country since the revolt against the government of President Bashar al-Assad erupted in mid-March 2011.
The violence has killed more than 15,000 people, the Syrian Observatory for Human Rights says.
On Monday, the Britain-based watchdog reported at least 41 people -- among them 29 civilians -- killed across Syria, as the army pounded rebel strongholds and other towns and cities.
Troops pounded the central city of Homs amid rebel Free Syrian Army warnings of an impending "massacre," and the opposition Syrian National Council urging international help "before it is too late."
In Geneva, International Committee of the Red Cross chief Jakob Kellenberger said security concerns were barring evacuations from Homs, which the Red Cross last week said it was hoping to undertake.
"There are real security concerns -- booby traps and other things," Kellenberger said, appealing to both sides of the conflict to give an "unambiguous agreement" to allow the evacuation to proceed.
Elsewhere, the Organisation of Islamic Cooperation recommended suspending Syria from the 57-member pan-Islamic body.