* Outgoing premier hospitalised with high blood pressure
* Early election likely in May, hung parliament probable
* Protests continue but size dwindling
SOFIA, Feb 27 (Reuters) - Outgoing Bulgarian Prime Minister Boiko Borisov has been hospitalised with high blood pressure, officials said on Wednesday, adding to a sense of political limbo before an interim government is appointed to take the country to early elections.
Borisov resigned last week after two weeks of sometimes violent protests by tens of thousands accusing the government of being a "Mafia" due to rampant corruption and its failure to improve living standards in the European Union's poorest state.
Demonstrators angry at high electricity prices attacked power company offices and three people set themselves on fire.
Hospital officials said on Wednesday Borisov was admitted with hypertension earlier this week, but should be discharged later in the day. A cabinet meeting due on Wednesday was postponed due the prime minister's absence.
Borisov's departure has failed to fully calm voters in a country where the average monthly wage is 400 euros ($520) and pensions less than half that. Demonstrations have continued on a smaller scale though large protests are planned for the weekend.
Other parties have declined to try to form a new government, meaning Borisov remains in office until an interim government is appointed, probably next week, which will take Bulgaria to elections expected in May.
Borisov's GERB party is now running neck-and-neck with the opposition socialists and neither is expected to win a majority.
"We need some new faces that have the energy and desire to revive the current parties," said Konstantin Haralampiev, 47, an entrepreneur in Sofia.
Borisov, a former bodyguard to communist dictator Todor Zhivkov, has maintained tight fiscal discipline, bringing the budget gap down to 0.5 percent of gross domestic product, important to maintain a currency peg to the euro.
But he has also risked a diplomatic row with the Czech Republic and EU by threatening to withdraw the licence of CEZ , one of three electricity producers along with another Czech company, Energo-Pro and Austria's EVN. Prosecutors are investigating of the companies' prices and any other possible malpractice.
The opposition socialist BSP is the successor party to the communists and its track record - having overseen a credit bubble that burst in 2009 and plunged the country into recession - may worry some investors.
The economy is only slowly recovering, with growth of about 1.4 percent expected this year, which does little to raise living standards.
"Political parties will now be concentrated on elections, not on protests that will gradually fade. People realise that the country was broke during the GERB reign," said Andrey Raichev, a political analyst with Gallup International.