Turkish President Abdullah Gul said on Saturday it was not possible to ignore the fact that Syria had shot down a Turkish fighter jet and said everything that needed to be done following the incident would be done, Turkish media reported.

"It is not possible to cover over a thing like this, whatever is necessary will no doubt be done," Gul told reporters from the central Anatolian city of Kayseri.

The Turkish military said it had lost contact with one of its F-4 fighter jets off the southern Turkish coast near Syria on Friday morning and Damascus later acknowledged it had shot the plane down.

Turkish Prime Minister Tayyip Erdogan, who had been returning from a summit in Brazil when the news broke, called an emergency security meeting on his arrival in Ankara and in a statement his office said Ankara would act "decisively" once all the details had emerged.

Syria has said the Turkish aircraft was flying low and well inside Syrian territorial waters when it was shot down. Gul said it was normal for jets to briefly cross into foreign airspace and said a probe into the incident would look at whether in fact it was downed while in Turkish airspace.

"When we think of the speed of these jet planes while flying above the sea, crossing over borders for a short distance and then back again is a little bit routine," said Gul.

He said because of the serious nature of the incident it was not possible at this stage to give any more detailed statement.

Asked whether Turkey was in contact with Syria over the incident, Gul said telephone contact had been made and said: "Because there is no security there, we withdrew our representatives from Syria. This does not mean there is no contact."

Gul said Turkish and Syrian forces were still working together to search for the two missing crew of the aircraft.

Ankara, which had drawn close to Syria before the uprising against Syrian President Bashar Assad, turned against the Syrian leader when he responded violently to pro-democracy protests inspired by popular upheavals elsewhere in the Arab world.

Turkey now gives refuge to the rebel Free Syrian Army on its frontier with Syria and is sheltering more than 30,000 Syrian refugees.

Ankara has previously floated the possibility of setting up some kind of safe haven or humanitarian corridor inside Syria, which would entail military intervention, but has said it would undertake no such action without UN Security Council approval.

Turkey has said, however, that Assad must step down.