The Syrian opposition has decided not to participate in Sochi summit and instead it announced that Turkey could do it on its behalf, according to a diplomatic source on Tuesday.

A delegation of the Syrian opposition arrived at the Sochi airport for the summit but later they changed their minds when they saw pictures with Syrian regime flags on it.

After the incident, they did decide not to enter the country and gave Turkey the authority to represent it on its behalf at the summit, the source, who asked not to be named due to restrictions on talking to the media, said.

Foreign Minister Mevlut Cavusoglu on Tuesday also confirmed Turkey would represent the Syrian opposition during peace talks in Sochi.

Talking to the media after attending the ruling Justice and Development (AK) Party's group meeting at the parliament in capital Ankara, Cavusoglu said: "It has been sorted out.

"The opposition has given its authorization to represent them [at Sochi] to Turkey," foreign minister said.

The foreign minister also said a constitutional commission would be established after the summit and Russia, Turkey and Iran would assign same number of members to it.

The commission will be chaired by UN's Special Envoy on Syria Staffan de Mistura.

Also on Tuesday, Foreign Minister Mevlut Cavusoglu and his Russian counterpart Sergey Lavrov spoke over the phone on the Syria process.

Foreign Ministry Deputy Undersecretary Sedat Onal will represent Turkey at the Sochi summit.

The Russian delegation will be headed by Moscow's envoy on Syria, Alexander Lavrentiev while the Iranian delegation will be led by Deputy Foreign Minister Hossein Jaberi.

On Dec. 22, Russian Foreign Minister Sergey Lavrov said all participants in the Syria talks in Geneva would be invited to the Sochi gathering.

The guarantor countries -- Russia, Iran and Turkey -- had agreed to gather for Syrian peace talks in southern Russian city of Sochi on Monday-Tuesday.

Syria has been locked in a vicious civil war since early 2011 when the Assad regime cracked down on pro-democracy protests with unexpected ferocity.

Since then, hundreds of thousands of people have been killed and more than 10 million others displaced, according to UN officials.