Referendum expanding Erdogan's powers confirmed for April

High Election Board head Sadi Guven said in a televised speech that the date was fixed after the law was published on the Official Gazette.

Erdogan signed the contentious law on Friday, clearing the way for public vote.

Guven said two colours – white and brown – would be used in ballot papers representing "yes" and "no" respectively.

The 18-article new constitution would create an executive presidency for the first time in modern Turkey.

The president will have the power to appoint and fire ministers, while the post of prime minister will be abolished.

The government says the far-reaching changes are needed for more effective leadership, but opponents fear they will drag Turkey into one-man rule.

Erdogan is seen by critics as increasingly autocratic after 14 years in power as both prime minister and president.