Energy cooperation has topped the agenda of a visit to Turkey earlier this week by the president of Turkmenistan, host to the world's fourth largest natural gas reserves.

"The cooperation of Turkey and Turkmenistan in energy field is important for the security of energy supplies," Mehmet Seyfettin Erol, professor of international relations at Gazi University, told Xinhua.

Turkmen President Gurbanguli Berdimuhamedov, who arrived in Ankara on Tuesday, cut short the visit and left for home on Wednesday, citing illness of his mother.

His Turkish counterpart, Recep Tayyip Erdogan, told a joint press conference that Turkey, Turkmenistan and Azerbaijan will elevate a trilateral energy cooperation mechanism from the foreign minister level to one that involves top leaders.

Erol, the Gazi University professor, said "if Turkmen gas is linked up with Azerbaijan and Turkey," the game may be changed in energy politics, he said.

At the joint press conference, Erdogan emphasized that Turkmenistan plays a key role in connecting Central Asian gas with international markets, and that the two presidents talked about transporting Turkmen gas to European markets through Turkey.

Turkey has been looking for ways to diversify its energy sources, especially seeking Azerbaijani and Turkmen gas from the Caspian Basin to meet both its growing domestic need and European demand.

Under a framework agreement signed during Erdogan's visit to Turkmenistan in November 2014, the two countries have already started construction of Trans-Anatolian Natural Gas Pipeline, for Turkmenistan to supply gas to Turkey. Endit