A notorious self-proclaimed Roma tsar, whose clan's impunity triggered unprecedented protests across the country over the last few days, has been arrested, authorities announced.

"Kiril Rashkov, aka Tsar Kiro, was detained and is currently in the town of Plovdiv," Interior Ministry Chief Secretary Kalin Georgiev told the morning broadcast of Nova TV channel on Wednesday.

Rashkov has been charged over murder threats and faces six years in prison if found guilty.

"Rashkov has been threatening the people from Katunitsa village even before the violent events over the last few days. The arrest has been made following a complaint for intimidation. If the boy was not killed, you might have not even heard that Rashkov is arrested and it would not be news, but he would have been arrested anyway," Georgiev commented.

The murder of Bulgarian youngster Angel Petrov, who was deliberately run over by a mini-bus driven by one of Rashkov's relatives, according to witnesses, led to massive protests of the ethnic Bulgarians in the village of Katunitsa. They culminated Saturday night into the burning of Rashkov's properties by football hooligans from Plovdiv, which is near to Katunitsa.

On Monday and Tuesday night, protests followed in many major Bulgarian cities, including the capital Sofia. Nearly 300 people in total were arrested by the police after the two nights of rallies that unfortunately involved what has been perceived as ethnic hatred.

Bulgarian authorities have frozen Rashkov's assets and property while he is investigated on tax evasion charges, the revenues agency has confirmed.