Last update: 09:51 | 25/06/2018
Turkey's long-standing leader Recep Tayyip Erdogan has won the country's presidential poll in the first round, the election authority chief says.
Sadi Guven said the president "received the absolute majority of all valid votes", but gave no further details.
State media reports put Mr Erdogan on 53% with 99% of votes counted, and his closest rival Muharrem Ince on 31%.
The opposition is yet to officially concede but said it would continue its democratic fight "whatever the result".
It had earlier cast doubt on results being broadcast by state media. Final results will be announced on Friday.
Mr Erdogan said the governing alliance of his AK Party had also secured a majority in parliament.
"Turkey has given a lesson in democracy to the entire world," he said.
Under Turkey's new constitution, due to come into force after the election, the president will hold considerable power.
Critics argue the enhanced role will see too much power accumulated in one person's hands, and that Turkey lacks the checks and balances of other executive presidencies such as France or the United States.
With 96% of the votes for parliament counted, the president's AK Party leads with 42% of the votes, the state news agency Anadolu reports. The main opposition CHP is on 23%.
Turkey's electoral board confirmed that the pro-Kurdish HDP has reached the 10% threshold needed to enter parliament. Before the vote, analysts said this might make it harder for Mr Erdogan's party and its ally the MHP to reach a majority, although currently they are on course to do so.
Voter turnout was high, at almost 87%, the state broadcaster reported.
"I hope nobody will try to cast a shadow on the results," Mr Erdogan said.
There are reports that CHP presidential candidate Mr Ince has admitted defeat in a message to a journalist, though this has not been confirmed.
Earlier on Sunday he accused state-run news agency Anadolu of "manipulation" over its reporting of vote-share figures. He said he would only comment when the official results had been announced.
Why does this election matter?
These elections were originally scheduled for November 2019 but were brought forward by Mr Erdogan.
The new president will be first to govern under the new constitution, endorsed in a tight referendum last year by 51% of voters.
While the other candidates have rejected the changes, Mr Erdogan would start his second term in a turbo-charged version of the job.
The job of prime minister would be scrapped and the president is set to gain new powers, including the ability to directly appoint senior officials and the power to intervene in the legal system.
What was the atmosphere during the campaign?
Mr Erdogan, whose party is rooted in Islamism, was prime minister for 11 years before becoming president in 2014, and correspondents said he had never faced such a tough election fight.
Mr Ince, a fiery centre-left candidate, electrified the campaign and drew huge crowds to his rallies. He accused Mr Erdogan of authoritarian rule.
In return the incumbent accused the former physics teacher of not having the skills to lead.
Mr Erdogan has moved to consolidate his power after a failed coup against his rule in 2016.
Turkey has been under a state of emergency ever since, with 107,000 public servants and soldiers dismissed from their jobs. More than 50,000 people have been imprisoned pending trial since July 2016.
There were another four candidates on the presidential ballot, none of whom looks to have performed particularly strongly.
As Mr Erdogan is declared to have won more than 50% of the vote, the presidential election will not go to a second round.
Was the vote fair?
Security was tight at polling stations. Ahead of the vote, concerns were raised about potential voter intimidation and electoral fraud.
Turkey's election commission has already said it will investigate alleged irregularities in Urfa province, on the southern border with Syria.
Mr Ince said he would be spending the night at the electoral commission's headquarters in Ankara to ensure a fair count. In a tweet, he asked election observers not to leave the ballot boxes.
Rights activists also said the press was not free to report on all sides.
Under Mr Erdogan's rule, the country has become the world's biggest jailer of journalists, according to monitoring groups.
What are the main issues?
The biggest is the economy. The Turkish lira has tanked and inflation stands at around 11%.
Terrorism is another vexed issue, as Turkey faces attacks from Kurdish militants and the jihadists of the Islamic State group.
However, correspondents say the country tends to vote along its big divides: one between Kurds and nationalists, and another between religious and secular people.