Turkey's Recep Tayyip Erdogan is ahead in the presidential election with 45% of votes counted, state media report.
Mr Erdogan has 57%, and his closest rival, Muharrem Ince, is on 28%.
If Mr Erdogan wins more than 50% of the overall vote, he will be declared the winner and avoid the need for a second round of voting.
As well as the presidency, voters are also choosing members of parliament. Mr Erdogan's party is ahead in that poll.
With 27% of the votes for parliament counted, the president's AK Party leads with 48% of the votes, the state news agency Anadolu reports. The main opposition CHP is on 18%.
Voter turnout is almost 87%, the state broadcaster says.
Initial results were thought likely to favour the AK Party, so Mr Erdogan's lead is expected to decrease as more votes are counted.
His opponent tweeted that the state news agency was being manipulative by releasing results from pro-Erdogan areas first.
Turkey remains under a state of emergency imposed in the aftermath of a failed coup in July 2016.
These elections were originally scheduled for November 2019 but were brought forward by Mr Erdogan.
He is seeking a second term as president, and would govern under a new constitution which grants the president new powers.
Mr Erdogan was prime minister for 11 years before becoming president in 2014.
bbc.com
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