* Protesters oppose sale of ailing railway operator's cargo unit
* Third man who set himself on fire died
* Urge president to carry audit on all privatisation deals
By Tsvetelia Tsolova
SOFIA, March 10 Hundreds of Bulgarian anti-corruption demonstrators took to the streets for a fourth straight Sunday, demanding a halt to the planned selloff of the state railway's cargo unit and an audit of all privatisation deals.
Street demonstrations brought down the centre-right government of Boiko Borisov last month and have continued since then, although numbers were smaller on Sunday, indicating protests may be losing steam.
The Balkan country is headed towards early election on May 12 with Borisov's party and Socialists neck-to-neck in opinion polls, making it likely that forming a government will be difficult and political uncertainty will continue.
Early on Sunday a 53-year old father of five who set himself on fire last month in desperation from poverty in the central town of Radnevo died from his burns, becoming the third victim of self-immolation since the protests started.
With average monthly salaries of just 400 euros ($520) and pensions half of that, Bulgarians have the lowest living standards in the EU. They blame consecutive governments for doing too little to improve their lives and fight rampant crime and corruption.
Waving national flags and chanting "Mafia" and "Let's get our the state back" about 600 protesters blocked all railway tracks at the central station in Sofia. About 1,000 people blocked rail tracks in the Black Sea city of Varna.
"The deal should be put off until there is a working government and parliament, so that the process be transparent and citizens can exercise controls," said Ivailo Vasilev, one of the organisers of the protest in Varna, referring to the planned privatisation of the cargo unit of railway operator BDZ.
Bulgaria is awaiting binding bids for the sale of the unit by March 12 in a deal estimated at about 100 million levs ($66.38 million). Proceeds will be used to ease BDZ's debts and allow it to tap a new loan from the World Bank.
But protesters fear the sale could be corrupt and lead to mass layoffs. They called on President Rosen Plevneliev, who is to form an interim government next week, to carry out an audit in all selloffs since the fall of communism two decades ago.
Dozens of people blocked the road to neighbouring Greece near the city of Blagoevgrad in protest against high utility bills and monopolies. Protests were held in at least 15 other cities.
The outgoing government cut electricity prices by an average of 7 percent and has launched a process to revoke the licence of power distributor CEZ, but these steps have failed to quell public discontent.
Plevneliev has pledged to appoint a technocrat caretaker government that will maintain fiscal stability.
($1 = 1.5066 Bulgarian levs) ($1 = 0.7703 euros) (Reporting by Tsvetelia Tsolova; Editing by Peter Graff)