Recep Tayyip Erdogan claimed victory in the Turkish presidential elections after initial results put him on course for an unprecedented third term in office.

"The only winner is Turkey," he said, addressing supporters from atop a bus in Istanbul.

Earlier the head of Turkey’s High Election Board said at a news conference that Mr Erdogan was leading Kemal Kilicdaroglu with 54.47 per cent support, with 54.6 per cent of ballot boxes logged.

‌Final results are expected at 8pm UK time.

Polls opened on Sunday morning in Turkey’s first-ever presidential run-off after Mr Erdogan failed to clear the 50 per cent bar two weeks earlier, leading four per cent ahead of his main rival.

Unlike two weeks earlier, polling stations in Istanbul on Sunday have not seen crowds or long lines of voters, mostly attributed to the fact that election officials need less time to process voters compared to the May 14 voting when Turks were also casting ballots in parliamentary elections.