Voting is under way in Turkey in a landmark referendum that will determine whether President Recep Tayyip Erdogan will be granted sweeping new powers.

Erdogan is seeking to replace Turkey's parliamentary system with an executive presidency, reports the BBC.

Supporters say the move would streamline and modernise the country, but opponents fear it could lead to greater authoritarianism.

A “yes” vote could also see Erdogan remain in office until 2029.

On Saturday, Turkish politicians made their final appeals to voters preparing to cast their ballots on one of the most sweeping programmes of constitutional change since Turkey became a republic almost a century ago.

Some 55 million people are eligible to vote across 167,000 polling stations, with the results expected to be announced late on Sunday evening.

If the referendum vote falls in Erdogan's favour, it would give him vastly enhanced powers to appoint cabinet ministers, issue decrees, choose senior judges and dissolve parliament.

Erdogan said the changes were needed to address the security challenges faced by Turkey, and to avoid the fragile coalition governments of the past.

Erdogan assumed the presidency, a largely ceremonial position, in 2014 after more than a decade as prime minister.

The referendum on constitutional change would abolish the post of prime minister altogether, allowing the president to bring all state bureaucracy under his control.

Opponents and critics of the proposed changes fear the move would make the president's position too powerful, arguing that it would amount to one-man rule, without the checks and balances of other presidential systems.

BDST: 1346 HRS, APR 16, 2017
AP