Anti-graft protest adds pressure to Slovenian prime minister

* Some 5,000 protesters rally against government

* PM hit by questions over sources of his income

* Coalition partners threaten to quit

By Marja Novak

LJUBLJANA, Jan 11 (Reuters) - More than 5,000 Slovenians gathered in the centre of Ljubljana on Friday to protest against a corruption scandal that threatens to bring down the government.

Slovenia's anti-corruption commission said earlier this week that Prime Minister Janez Jansa had been unable to explain the source of some of his income in recent years.

Jansa, who denies the income was of suspicious origin, has retained the support of his centre-right Slovenian Democratic Party, but two minor partners are considering quitting the coalition, something likely to force an early election.

Revived protests against corruption and budget cuts, which spread around Slovenia in November but calmed down in December, could give additional motivation for junior coalition parties to quit the government.

The protesters carried banners with slogans such as: "Together for the resignation of the government ... Those who stole from us should be punished."

"They are stealing but nevertheless want to cut our wages. That cannot be! They have to go!," said one of the protesters, a 45-year-old school teacher who gave her name as Maja.

The government plans to cut public sector wages by 5 percent this year to reduce the euro zone country's budget deficit to around 3 percent of GDP, from 4.2 percent in 2012.

The anti-corruption commission said Zoran Jankovic, leader of the opposition Positive Slovenia and the mayor of Ljubljana, was also not able to explain the origin of a part of his income. Jankovic, too, denied any wrongdoing.

"It is impossible to say what will happen but we are really very close to the fall of the government," Tanja Staric, an analyst of daily Delo, told Reuters.

"An early election is the most likely outcome and if that happens we would probably have the new government only in June or July."

That could further delay economic reforms and lead to more cuts to Slovenia's credit ratings which have been falling steadily over the past 16 months amid political instability.

Parliament ousted the previous, centre-left, government over its inability to implement economic reforms and an election in December 2011 brought Jansa's 5-party coalition to power with a slim majority of 49 seats in a 90-seat parliament.

Junior coalition party Civic List, led by parliamentary speaker Gregor Virant, which is most likely to quit over the corruption scandal, has seven seats, so its exit would leave the government without a majority and could prompt other coalition parties to quit.

Slovenia was badly hit by the global economic downturn due to its dependency on exports and fell into a new recession in 2012 amid lower export demand and a fall of domestic spending due to budget cuts.

In October Slovenia managed to issue its first sovereign bond in 19 months, averting an EU bailout for at least six months. (Reporting By Marja Novak; Editing by Robin Pomeroy)