State run news agency reports a narrow victory for Yes, while opposition parties call for a recount.
Supporters of President Erdogan have begun celebrations in Istanbul as results of the much-awaited referendum came in.
Speaking at the AK party HQ, prime minister Yildirim said that unofficial results show Yes is ahead in the referendum. Addressing supporters he said Turkey is ‘opening a new page in its democratic history’.
The state-run Anadolu Agency reported a vote in favour of changes that would give the president sweeping new powers. It said the Yes camp had won by a narrow margin of 51% with more than 95% of ballot boxes opened.
However, the main opposition parties have called the vote into question. The Republican People’s Party said that ‘illegal acts’ were being carried out in favour of the government.
The pro-Kurdish HDP also said that the result would remain unclear until its appeal to the High Electoral Board over vote irregularities was finalised.
It comes after Turkey’s Electoral board said it would allow ballots that had not been stamped by officials, unless they could be proved fraudulent, citing a number of complaints that officials had failed to stamp them.
Despite calls for recounts, Erdogan appeared to have suffered a setback in the biggest city Istanbul, where the No looked set to win, followed by a shift to No in Ankara.