SOFIA (Reuters) - The Bulgarian Socialist Party (BSP) pledged to speed up economic growth and fight corruption when it presented its program on Sunday for the early parliamentary election in March.

Socialist ally Rumen Radev, a Russia-friendly newcomer to politics, won the presidential election by a wide margin in November, prompting center-right Prime Minister Boiko Borisov to step down.

The resignation triggered a snap parliamentary poll set for March 26 - the third in three years - that analysts say may again fail to produce a stable majority government in the European Union's poorest member state.

The BSP's election program includes the ambitious goal of achieving economic growth of no less than 12 percent over four years. Bulgaria's economy grew by 3.4 percent in the third quarter of 2016 from a year earlier.

The Socialists vowed to make a significant improvement in living standards. More than a quarter of Bulgaria’s 7.2 million people live below the poverty line and many Bulgarians have moved abroad in recent times.

In its election manifesto the center-right GERB party promised on Friday to boost the average monthly salary by over 50 percent to 1,500 levs ($824) over four years, to double teachers' salaries and to keep corporate and income taxes unchanged at 10 percent.

The BSP, heir to Bulgaria's once-mighty Communist Party, plans to introduce a 20-percent tax for people with an annual income of over 120,000 levs, tax breaks for young entrepreneurs and interest-free credits for young families to purchase a home.

Bulgaria was ranked the EU's most corrupt country in Transparency International's 2016 Corruption Perceptions Index and has been rapped repeatedly by Brussels for failing to combat rampant organized crime and to jail high-level officials.

"The mafia, corruption, the wrong transition model have their own parallel state," Kornelia Ninova, the first female leader in the BSP's 126-year history, told delegates at the party's 49th congress. "We will close down this parallel state."

The BSP came second in the 2014 parliamentary election, collecting 18.3 percent of the vote. Now the Socialists are neck-and-neck with GERB, a recent Gallup International poll showed.

On Friday, Ninova said that Bulgaria will "categorically" seek a lifting of European Union sanctions against Moscow if her party wins the election.

The Socialists are also considering restarting some Russian projects, including the Belene nuclear power project. Bulgaria pulled out of the project in 2012 because of its costs and concerns over increased energy dependence on the Kremlin.

(Reporting by Angel Krasimirov; Editing by Andrew Bolton)