UN Secretary-General Ban Ki-moon has called for Turkey and Syria to exercise restraint over Syria's downing of a Turkish jet fighter over the Mediterranean.
"The secretary-general is following the situation closely. He hopes this serious incident can be handled with restraint by both sides through diplomatic channels," Mr Ban's spokesman Martin Nesirky.
His comments come after Turkey promised to do "whatever necessary" in response to Syria's shooting-down of a Turkish military plane.
Turkish foreign minister Ahmet Davutoglu held a meeting with commanders from Turkey's military and the head of the intelligence service to discuss what steps Turkey would take.
The meeting lasted two hours and was attended by the military's deputy chief of staff, senior military commanders and the head of the National Intelligence Agency, who also discussed the search operation for the missing pilots.
The downing of the aircraft, at a point close to the sea borders of both countries, provided a demonstration of Syria's formidable Russian-supplied air defences; one of the many reasons for Western qualms about any military intervention to halt bloodshed in the country.
Ankara's once-friendly relations with Damascus had already turned icy over president Bashar al-Assad's violent crackdown on a 16-month-old revolt, but signals from both sides suggested neither wanted a military confrontation over the incident.
"It is not possible to cover over a thing like this, whatever is necessary will be done," Turkish president Abdullah Gul said, according to state news agency Anatolia, adding that Ankara had been in telephone contact with Syrian authorities.
He said it was routine for fast-flying jets to cross borders for a short distance and that an investigation would determine whether the F-4 fighter was brought down in Turkish airspace.
Syria's military said the Turkish aircraft was flying low, just one kilometre off the Syrian coast, when it was shot down.
"The navies of the two countries have established contact. Syrian naval vessels are participating along with the Turkish side in the search operation for the missing pilots," it said.
With the second biggest army in NATO, a force hardened by nearly 30 years of fighting Kurdish rebels, Turkey would be a formidable foe for a Syrian military already struggling to put down a popular uprising and an increasingly potent insurgency.
Turkish prime minister Tayyip Erdogan chaired an emergency security meeting on Friday evening after which his office said it is "understood" that Syria had downed the plane and confirmed that both sides were searching for the two missing airmen.
"Turkey will present its final stance after the incident has been fully brought to light and decisively take the necessary steps," said a statement from Mr Erdogan's office.
Turkish newspapers were less restrained.
"They (the Syrians) will pay the price," said Vatan, while Hurriyet daily said "He (Assad) is playing with fire."
The joint Turkish-Syrian search and rescue operation sits uneasily with Turkey's hosting of the rebel Free Syrian Army fighting to topple Dr Assad, once a personal friend of Mr Erdogan.
Reuters