Turkey’s main opposition party has warned it could walk out of parliament in protest at alleged fraud in Sunday’s referendum, significantly raising the stakes in its standoff with President Recep Tayyip Erdogan over the disputed results.

The secular Republican People’s Party (CHP) issued its warning as dozens of opposition activists were arrested for protesting the referendum result in what appeared to be a fresh political crackdown.

Mr Erdogan meanwhile said he intended to press ahead with translating the narrow Yes vote into constitutional reforms that will give him sweeping new powers and brushed off criticisms that the changes would take Turkey towards dictatorship.

Three days after Mr Erdogan’s Yes camp claimed a 51 per cent victory in the historic referendum, the furore over alleged voter fraud showed no signs of dying down.