Erdogan camp set to win after most votes counted

Turks have backed President Recep Tayyip Erdogan's call for sweeping new presidential powers, partial official results of a referendum indicate.

With about 99.6% of ballot boxes opened, "Yes" was on about 51.2% and "No" on about 48.7%, according to local media.

Erdogan supporters say replacing the parliamentary system with an executive presidency would modernise the country.

Opponents have attacked a decision to accept unstamped ballot papers as valid unless proven otherwise.