Tbilisi, Mar 26 (IANS/RIA Novosti): Lawmakers in Georgia have approved changes to the constitution that will reduce President Mikheil Saakashvili's authority and tip the balance of power to the prime minister.

The changes, which include stripping the president of the right to dismiss the government without parliamentary approval, mark a new victory for billionaire prime minister Bidzina Ivanishvili, whose Georgian Dream coalition triumphed in the October elections.

Saakashvili's 65-member United National Movement minority faction backed the bill in its third and final reading, but only after a non-binding test vote aimed at demonstrating its support would be needed to push through the changes in the 150-seat parliament.

The two-thirds majority required for changes to the constitution was not reached in the test vote.

Once political allies, Ivanishvili and Saakashvili have become sworn enemies and have over the past few months traded increasingly bitter barbs.

The bitterly fought parliamentary election campaign spelled the start to Saakashvili's political decline.

The office of the president was due for an automatic downgrade later this year under earlier agreed constitutional reforms, but Georgian Dream lawmakers said they did not want to run the risk of Saakashvili dismissing the government.

"I was never going to dismiss the government or the parliament ... But this vote was important for democratic dialogue in our country," Saakashvili said earlier, after initial parliamentary backing for the amendments.

Saakashvili is due to stand down as president after his second term ends in October.