Bulgaria's ousted centre-right extends lead before May poll

Support for GERB, led by former Prime Minister Boiko Borisov, stood at 21.9 percent in March, up from 20.9 percent in January, while backing for the Socialists fell to 17.4 percent, according to the poll.

Tens of thousands of people protested in the European Union's poorest country against rising unemployment and high utility bills, leading to Borisov's resignation. The Balkan country will hold parliamentary elections on May 12.

"The resignation of Borisov's government has led to consolidation among GERB's supporters and has increased their resolution to vote," Alpha Research said in its survey.

The nationalist Attack party was the biggest beneficiary from the protests against high utility prices and low living standards, with support rising to 5.5 percent from 1.9 percent in January, according to the poll of 1,050 people carried out from March 22-27.

Assuming turnout of about 55-57 percent, Alpha Research estimated GERB would take 35-38 percent of actual votes and the Socialists around 30 percent, indicating a hung parliament was the likely outcome of the election.

A party would need to win above 43 percent of the actual votes to hold a parliamentary majority.

The protesters have failed to unite behind one political party and although several different factions will now run for parliament, it is yet not clear whether they will gather enough support to reach a 4 percent threshold to enter parliament.

The poll showed a unified protesters' party could reach 14 percent support.

Bulgarians live on an average monthly wage of 400 euros (342.24 pounds) and pensions of less than half that. Unemployment hit 12 percent in February, its highest since April 2005.

(Reporting by Tsvetelia Tsolova; Editing by Sophie Hares)