* Rallies across Bulgaria after government ousted
* New election expected by May
* Electricity bills at times exceed incomes
By Tsvetelia Tsolova
SOFIA, Feb 24 (Reuters) - Tens of thousands of people marched in cities across Bulgaria on Sunday, demanding an end to high utility bills and new voting rules after the government was toppled last week.
Public anger with power monopolies in the European Union's poorest member forced right-of-centre Prime Minister Boiko Borisov's cabinet to resign and has put the country on track for an early election by May.
Although Borisov's government managed to maintain fiscal stability since taking power in 2009, belt-tightening has held back growth and driven up unemployment.
His departure has failed to calm voters fed up with low living standards and rampant graft, and his GERB party is now running neck-and-neck with the opposition Socialists ahead of the new election.
The last straw for many was a jump in winter electricity bills that at times exceeded incomes in a country where average salaries are just 400 euros ($530) a month and pensions are less than half that amount.
Much of the anger has been directed at power companies including Czech CEZ and Energo-Pro and Austria's EVN, which bought exclusive rights to distribute energy in specific regions from Bulgaria in 2004.
Waving Bulgarian flags and slogans reading "Fighting for decent life" and "Down with monopolies" over 10,000 Bulgarians marched through downtown Sofia.
"For years and years the politicians failed to impose strict controls over monopolies. This should stop," said 54-year-old Irena Mitova, a shop owner in Sofia.
Demonstrations also took place in around 40 other cities, with some 15,000 people marching in Bulgaria's second and third largest cities Plovdiv and Varna.
Separate, smaller protests were held against an inefficient education system that critics say does not prepare students for the labour market and against high interest charges from retail banks criticised for hurting small businesses.
President Rosen Plevneliev, who will probably appoint a caretaker government and dissolve parliament next week to pave the way for the early election, met protesters and ensured them their voices would be heard.
Protesters' demands ranged from imposing a moratorium on paying electricity bills for December and January until audits are carried out to sweeping changes in the constitution to allow the direct vote for deputies, rather than using party lists.
Some of the protesters demanded parliament continue with its work to adopt laws to ensure strict controls over the energy monopolies. Many want them to be renationalised and say politicians sold firms since the fall of communism in 1989 in a way that hurt public interest and kept living standards low.
Borisov had promised an 8 percent cut in electricity bills as of March - reversing much of a 13 percent rise his government approved last year - and has said the energy regulator would begin the process to revoke CEZ's licence.
The regulator said a possible price decrease could be introduced as of April at the earliest and suggested there was room for compromise with CEZ. ($1 = 0.7598 euros) (Editing by Michael Winfrey and Alison Williams)