At least 15 people were injured Monday in clashes between demonstrators and police in this capital during the ninth consecutive day of protests over the recent 13 percent hike in electricity rates, according to state-run BNT television.

Interior Ministry officials consulted by Efe said that 11 people were arrested and two police officers were injured.

They added that preliminary information indicates that several windows in the Parliament building were broken, a number of trash bins' contents were strewn on the streets and burned and four police cars were damaged.

Sofia police chief Valeri Yordanov, as quoted by the Focus news agency, said that about 1,500 people participated in the protest.

Yordanov added that none of the injured was seriously hurt, and although he declined to give a specific number of those casualties various media outlets reported that the injured numbered anywhere between two and 15-plus.

Insofar as Efe could verify, the demonstrators - most of them young and organized via the Facebook social network - first blockaded a main street in Sofia, cutting traffic there, and then headed for Parliament.

The violence erupted when police and specially deployed anti-riot squads tried to prevent the demonstrators from approaching the legislative seat, prompting as many as 150 youths - as calculated by the Mediapool news agency - to hurl stones and bottles at law enforcement personnel and at Parliament itself.

From there, the demonstrators fanned out and tipped over trash dumpsters, burning the contents of at least seven of them, according to the private Darik radio network.

There were similar protests, although apparently they did not degenerate into physical violence against police, in other Bulgarian cities, including Varna, Plovdiv, Haskovo, Dimitrovgrad and Pernik, but the demonstrators did throw stones and eggs at the offices of power companies.

Bulgaria is the European Union's poorest country, but its people have been dealing with a 13 percent hike in electricity rates since July and a harsh winter that has raised power consumption.

According to President Rosen Plevneliev, Bulgarian society's "big problem" right now is the perception among the public of "injustice" and the low income level, and he has called upon the political parties to "abandon slogans and propose concrete initiatives" to resolve the country's problems. EFE