The Central Election Commission said 63% of people had voted in favour of the referendum, a far bigger margin of victory than polls had predicted in the run up to the vote.

But Armenia’s opposition said that the vote had been rigged and urged an investigation, a move supported by the US embassy.

Hundreds of people gathered in Yerevan’s central square after the referendum to protest again the result.

Turnout at the vote, though, was reportedly low, despite the high-profile nature of the reforms. Some analysts said the low turnout betrayed people’s belief that the changes had been brought in to improve the position of the ruling elite rather than update the political system.

Lilit Gevorgyan, an analyst at IHS, said that shifting to a parliamentary system was dressed up as a progressive move but was in fact a way for the political and economic elite to shore up their positions.

“It’s an innovative way of solving the succession issue,” she said.

The new rules are set to be introduced at a parliamentary election in March 2017. Mr Sargsyan is set to leave the presidency in 2018.

As well as handing a slimmed down parliament of 101 members elected via proportional representation more power, the new constitution builds in a run-off system which will ensure a majority for a single party.

This last issue was also contentious.

The reformists argued that this system avoided weak minority governments. Its opponents said it bordered on a form of totalitarian rule.