Saudi Foreign Minister Adel al-Jubeir and his Turkish counterpart Mevlut Cavusoglu on Sunday voiced support for Syrian opposition figures who have travelled to Geneva for UN-brokered peace talks.

"We share the same position which consists of supporting our Syrian brothers directly or when they take part in international meetings," Jubeir said in Riyadh at a joint news conference with Cavusoglu.

Turkey's top diplomat echoed him, saying: "We back demands for a truce and for sending humanitarian aid" to besieged towns in Syria as requested by the opposition.

The opposition Higher Negotiations Committee had threatened to boycott the talks involving Syrian government representatives which opened Friday in Geneva unless a host of conditions was met.

A delegation from the HNC arrived late Saturday in the Swiss city and on Sunday some members met UN envoy Staffan de Mistura.

"We only came to Geneva after written commitments on the fact that there would be serious progress on the humanitarian issues," HNC spokeswoman Basma Kodmani told reporters.

"We are here for political negotiations but we cannot start those until we have those gestures," she said.

Saudi Arabia and Turkey are both opposed to the Syrian regime of President Bashar al-Assad and have called for his removal from power.

Sunday's joint Saudi-Turkish news conference came as Turkish Prime Minister Ahmet Davutoglu wrapped up a three-day visit to the oil-rich kingdom and met King Salman.

Jubeir told reporters that Riyadh and Ankara have agreed to set up a "strategic cooperation council" to coordinate their positions, including in "the battle against terrorism, politics, security and military affairs".