Bulgaria parliament set to abandon new nuclear plant

* Turnout too low to validate referendum result

* Government wants to abandon Russia-backed project

* Opposition will push ahead if its wins July election

By Tsvetelia Tsolova

SOFIA, Jan 29 (Reuters) - Bulgaria's government will use its majority in parliament to enforce its decision not to build a new nuclear power plant, despite Bulgarians backing its construction in a referendum just months before a national election.

Although 60.6 percent of those who voted supported building the plant at Belene on the Danube, hoping it would create jobs and cut power bills, official data on Tuesday showed turnout on Sunday was 20.2 percent - too low to make it binding.

Because turnout scraped over the 20 percent threshold, and more than half of those voted in favour, the issue now has to return to parliament - dominated by allies of rightist Prime Minister Boiko Borisov - for a final decision.

Bulgaria's allies in Brussels and Washington opposed the project, fearing it would deepen the country's economic and political dependence on Russia after Moscow offered to finance the plant which would have been built by its Atomstroyexport.

Speaking to foreign investors on Tuesday, Borisov, who had abandoned the project on the grounds of cost and a lack of Western investor interest, confirmed plans to instead build a reactor at Bulgaria's operational Kozloduy nuclear plant and to extend the lifespan of its two existing 1,000-megawatt reactors until 2030.

The referendum nonetheless has eroded some support for Borisov, a former bodyguard who came to power in 2009 promising to crack down on corruption and organised crime but who has made little progress and faces an election in July.

The opposition Socialists, who called the referendum, said they would push ahead with Belene if they win the parliamentary election as the new plant will boost the economy, cut electricity costs and create well-paid jobs.

"I cannot guarantee the fiscal stability of Bulgaria after July, because if the Socialists win the elections and push ahead with Belene ... who knows what the fiscal framework of the state will be," Borisov said.

Austerity and high unemployment have also knocked Borisov's ratings and though his GERB party remains the most popular political faction with about 24 percent of support, the Socialists have closed the gap and have some 20 percent backing.

That suggests the election could result in a split parliament and horse-trading with a host of smaller parties including an ethnic Turkish MRF party and the rightist party of former EU Commissioner Meglena Kuneva, Citizens For Bulgaria. (Editing by Alison Williams)