The people of Turkey have made a "historic decision" by saying "yes" to constitutional amendments that will increase the power of the presidency, Turkish President Recep Tayyip Erdogan said on Sunday evening in Istanbul.
His speech came soon after Prime Minister Binali Yildirim declared victory for the "yes" camp in the referendum, despite there being no official result.
"The entire country has triumphed," Erdogan said, adding that the new system of government would not be implemented immediately, but after elections in 2019.
"The Turkish people have given the final word by saying 'yes'," Yildirim said in Ankara at the headquarters of the ruling Justice and Development Party (AKP).
State news agency Anadolu is showing the "yes" vote ahead by 51.4 per cent, compared to 48.6 for the "no" camp, in the tight race with more than 99 per cent of ballots counted.
Opposition parties, including the main opposition People's Republican Party (CHP) and the pro-Kurdish Peoples' Democratic Party (HDP), have vowed to challenge the result.
