The UN-Arab League envoy for Syria, Lakhdar Brahimi, is due to hold talks in Turkey, amid rising tensions between Ankara and Damascus.
Mr Brahimi will hear Turkey’s perspective on the raging crisis from Foreign Minister Ahmet Davutoglu.
Several days of cross-border firing followed the killing of five Turkish civilians by Syrian shelling last week.
Earlier this week, Turkey intercepted a Syria-bound plane amid reports it had Russian-made defence equipment aboard.
Syria has dismissed the claim as a lie, challenging Turkey to show any evidence.
And in Syria itself, activists said on Friday that rebel fighters had seized a government air defence base near the embattled north-western city of Aleppo.
The claim has not been independently verified.
‘No obvious plan’
Mr Brahimi is due to meet Mr Davutoglu in Istanbul later on Saturday. German Foreign Minister Guido Westerwelle, will also have talks with his Turkish counterpart.
“It is important that no one pours oil on the fire. We are counting on moderation and de-escalation,” the German minister said, according to news agency AFP.
Turkey may not be at war with Syria, but it is now increasingly involved in its neighbour’s conflict, the BBC’s James Reynolds in Turkey reports.
The government of Syrian President Bashar al-Assad accuses Turkey, along with Saudi Arabia and Qatar, of arming the rebels.
However, Syria has said it is ready to set up a joint committee to oversee security on the border.
Its foreign ministry said it had been discussing with diplomats from Russia, a key ally, the idea of a Syrian-Turkish security committee to avoid misunderstandings at the border, which would establish a “mechanism for surveillance of the border while respecting national sovereignty”.
Mr Brahimi’s visit comes a day after he met senior Saudi officials in the city of Jeddah.
Saudi Deputy Foreign Minister Prince Abdel Aziz bin Abdullah was quoted as urging for “an immediate halt to the bloodshed of the Syrian people”.
However, the envoy’s visit to the region carries no immediately obvious peace plan, our correspondent says.
He adds that UN Secretary General Ban Ki-moon has suggested Mr Brahimi may head to Damascus next week if his meetings in the region go well.
But speaking on Saturday, Turkish PM Recep Tayyip Erdogan, criticised the UN Security Council for being ineffective in dealing with the conflict in Syria.
“If we leave the issue to the vote of one or two members of the permanent five at the United Nations Security Council , then the aftermath of Syria would be very hazardous and humanity will write it down in history with unforgettable remarks,” he said.
“It’s high time to consider a structural change for international institutions, especially for the UN Security Council.”