Turkey referendum: First results show Erdogan camp set to win
Egypt: With more than 50% of ballots counted, the “Yes” vote was on 58% and “No” on about 42% but the results may not be representative of the entire country.
Erdogan supporters say replacing the parliamentary system with an executive presidency would modernise the country.
But opponents fear it could lead to greater authoritarianism.
A “Yes” vote could also see Mr Erdogan remain in office until 2029.
Three people were shot dead near a polling station in the south-eastern province of Diyarbakir, reportedly during a dispute over how they were voting.
About 55 million people were eligible to vote across 167,000 polling stations.