Updated at 8:50 a.m. ET: Turkish President Abdullah Gul said on Saturday it was not possible to ignore the fact that Syria had shot down a Turkish military jet and said everything that needed to be done following the incident would be done, Turkish media reported. 

Gul said it was routine for jets travelling at high speed to cross borders for a short distance. He said an investigation into the incident would look at whether the plane was downed in Turkish airspace, media reported. 

Gul also said Ankara had been in telephone contact with Damascus and that a search operation for the plane and missing pilots was still under way. 

"It is not possible to cover over a thing like this, whatever is necessary will be done," Gul was quoted as saying by state news agency Anatolia.

Faruk Celik, Turkey's Labor and Social Security Minister, said Turkey would retaliate "either in the diplomatic field or give other types of response." 

"Even if we assume that there was a violation of Syria's airspace — though the situation is still not clear — the Syrian response cannot be to bring down the plane," Celik told reporters. "The incident is unacceptable. Turkey cannot endure it in silence." 

Syria said Friday its forces had shot down a Turkish military plane that entered its air space. The plane, an unarmed F-4, went down in the Mediterranean Sea about 8 miles away from the Syrian town of Latakia, Turkey said. 

It was initially reported to be a fighter jet, but Turkish Deputy Prime Minister Bulent Arinc said Saturday it was a reconnaissance aircraft, state television TRT reported. 

The incident further escalated tensions between Syria and NATO-member Turkey. The two neighbors used to be allies before the Syrian revolt began in March 2011 but Turkey has become one of the strongest critics of the Syrian regime's brutal response to the country's uprising and is playing host to civilian and military Syrian opposition groups. 

'Necessary' action will be taken
Gul said that Turkey was still trying to establish the exact circumstances of the incident but said jets flying at high-speeds would at times violate other countries' air spaces for short periods of time. 

"These incidents are routine," Gul said. "They are incidents that are not ill-intentioned and happen because of the speeds (of the jets)." 

"Was that the case, or did (the incident) occur in our own air space, these facts will emerge," he said. "No one should have any doubt that whatever (action) is necessary will be taken." 

Gul did not elaborate on what those steps would be. But Turkey said after a border shooting incident — which killed two people inside a Turkish refugee camp in April — that it would call on its NATO allies to intervene should it feel that its security was being threatened. 

Syrian coast guards joined Turkish coast guards in their search for the jet's two missing crew members for a second day on Saturday, Turkey's private NTV reported. Some pieces of the wreckage had been found, Gul said, without elaborating. 

Late Friday, Syria's state-run news agency, SANA, said the military spotted an "unidentified aerial target" that was flying at a low altitude and at a high speed. 

"The Syrian anti-air defenses counteracted with anti-aircraft artillery, hitting it directly," SANA said. "The target turned out to be a Turkish military plane that entered Syrian airspace and was dealt with according to laws observed in such cases." 

Syria claimed the jet violated its air space over territorial waters, penetrating about 0.62 miles. It said Syria forces realized that it was a Turkish jet after firing at it. 

On Saturday, a top-selling Turkish newspaper, Hurriyet, accused Syria of "Playing with Fire" in its banner headline, while Vatan newspaper said Syria would "pay the price" for the attack.

Reuters and The Associated Press contributed to this report.

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