The Greek prime minister has sealed a surprise agreement that will separate the state from the powerful Orthodox Church for the first time in centuries.

Alexis Tsipras, who is an atheist, reached agreement on Tuesday with Archbishop Ieronymos II, the head of the Greek Orthodox church, to redefine the state as “religiously neutral”. The constitution had long stipulated that the Greek Orthdox faith was the dominant religion in the country.

The move fulfils a long-standing election campaign pledge to modernise the Greek state, which Mr Tsipras hopes will help to lure back thousands of disgruntled voters next year.

The deal will save the Greek Treasury about €200 million a year by stripping some of the country’s 10,000 priests and church staff of their state-funded salaries,