Turkish president Recep Tayyip Erdoğan claimed a narrow victory in Sunday’s referendum on whether to give him sweeping new powers, but Turkey’s opposition said they would contest the result over fears of voter fraud.

In a dramatic finish to the bitterly-fought referendum campaign, the state-run news agency said Mr Erdoğan’s Yes camp had won around 51 per cent while the No campaign took 49 per cent with 98 per cent of the vote counted.

Mr Erdoğan claimed victory in a low-key speech in Istanbul in which he appealed for unity. “This is a historic decision, not an ordinary event,” he said. “We are carrying out the most important reform in the history of our nation.”

Mr Erdoğan said he would immediately begin looking at restoring the death penalty, a move that would end any possibility of Turkey joining the EU.

But the opposition CHP party said it was looking to contest 37 per cent of the ballot boxes over suspicion of vote tampering.