A Turkish police officer checks identification cards of Syrian men after they crossed from Syria to Turkey at the Akcakale border gate. - Reuters

UN Secretary-General Ban Ki-moon has again expressed concern that the offensive between Syria andTurkey may spill over to neighbouring countries.

Condemning the Syrian mortar attack which killed five Turkish civilians, Ban said he was alarmed by the escalating situation in the border region.

A statement released by Ban's spokesperson said: "The secretary-general is alarmed by escalating tensions along the Syrian-Turkey border. The secretary-general has repeatedly made clear his concern about the spillover of the Syrian crisis into neighbouring countries, as occurred yesterday with Turkey."

A recent secret Syrian document also revealed that the Turkish pilots who were thought to have died in a crash were actually said to have been executed on President Bashar al-Assad's orders.

The Security Council also condemned the attack saying it threatens regional peace and stability.

Calling on both sides to show restraint, current president of the council ambassador Gert Rosenthal of Guatemala said: "The members of the council demanded that such violations of international law stop immediately and are not repeated. The members of the Security Council called on the Syrian government to fully respect the sovereignty and territorial integrity of its neighbours."

The statement has come after an initial strongly-worded report was rejected by Russia. Although the Russian version of the draft was not taken, the original report was diluted accommodating the concerns of Syria's key ally, Moscow.

The members of the council "underscored that the incident highlighted the grave impact the crisis in Syria has on the security of its neighbours and on regional peace and stability."

Responding strongly to recent developments in Syria, the Turkish government has authorised military action inside Syria but tempered it with caution.

"The Turkish Republic is a state capable of defending its citizens and borders. Nobody should try and test our determination on this subject," said Turkish Prime Minister Recep Tayyip Erdogan at a press conference in Akcakale. Erdogan was speaking soon after the country's parliament approved border operations during an emergency vote.

Syrian ambassador at the UN Bashar Jaafari criticised that the council did not condemn the suicide attacks in Aleppo which killed many security forces. The Aleppo bombings took place on the same day the mortar attacks were launched.

Although Assad offered the Syrian government's condolences for the death of Turkish civilians, he stopped short of tendering an apology claiming investigations are still on.