ANKARA, June 24 (Xinhua) -- Preliminary results showed Turkey's incumbent President Recep Tayyip Erdogan won 52.5 percent of votes in the presidential race with 97.9 percent of votes counted, state-run Anadolu Agency said Sunday.

Erdogan's main presidential rival, Muharrem Ince of the main opposition Republican People's Party (CHP), stood at 30.7 percent.

The ruling Justice and Development Party (AKP) had 42.4 percent in parliamentary elections. In the opposition camp, CHP had 22.7 percent of votes, according to Anadolu Agency's unofficial results.

The pro-Kurdish Peoples' Democratic Party (HDP) candidate Selahattin Demirtas, who ran his campaign from jail where he is being held pending trial on terrorism-related charges, was garnering 11.4 percent.

President Erdogan declared victory in Istanbul on Sunday evening, claiming that he has been entrusted by the nation with the task and duties of the presidency.

However, the opposition raised doubts about the accuracy and reliability of the figures released by Anadolu Agency.

CHP spokesman Bulent Tezcan told reporters in Ankara on Sunday evening that the presidential race has gone to a second round, calling on supporters to spend the night in electoral offices across the country.

The presidential and parliamentary elections will complete Turkey's transition from a parliamentary system to a new executive presidential one, a move approved in a referendum last year.

Some 59 million Turks cast their votes in more than 180,000 ballot boxes across the country.

The turnout was quite high at around 87 percent for both contests, the state broadcaster TRT said.

The elections have also been held under a state of emergency imposed in the wake of the failed coup in July, 2016.