The main Turkish opposition party on Sunday claimed victory in the mayoral race in the capital Ankara as the party built a solid lead in the count for control of Istanbul, according to partial results from local elections.

In Ankara, mayor Mansur Yavas of the Republican People's Party (CHP) said "The elections are over, we will continue to serve Ankara".

Yavas was leading with 58.6 per cent of the vote to 33.5 per cent for his opponent from the country's ruling Justice and Development Party (AKP), from 46.4 per cent of ballot boxes opened.

In Istanbul, with more than 71 per cent of ballot boxes opened, current mayor Ekrem Imamoglu, also of the CHP, had 50.4 per cent of the vote to his AKP rival's 40.9 per cent.

"Voters have chosen to change the face of Turkey," said CHP chairman Ozgur Ozel as the results emerged. "They want to open the door to a new political climate in our country."

The country has been dominated for more than two decades by the AKP of President Recep Tayyip Erdogan. The veteran president had launched an all-out campaign to win back Istanbul, which was lost to the ChP in 2019.