The Bulgarian Prosecutor's Office has submitted the indictment against the chief of a Sofia police unit and six of its members to the Specialized Criminal Court, officials say.

Prosecutors allege they were involved in an organized criminal gang which had been active from December 2012 to the summer of last year when they were detained.

Supposedly, it was Ivaylo Vasilev, the head of the Sigma unit, who set up the gang, according to a statement the prosecuting authority published on its website.

Prosecutors believe Vasilev talked his subordinates into taking part in the scheme by promising them protection.

The group's members are said to have forced drivers who committed traffic offenses into paying hefty bribes in order to avoid other sanctions.

Vasilev allegedly send them to patrol along routes where traffic offenses were not uncommon, which resulted in a minimum of BGN 200-400 (EUR 100-200) received by a team (2-3 police officers).

In cases when drivers lodged bribery complaints, Sigma's chief used his influence to avoid any consequences for the members.

Sigma policemen are responsible for maintaining public order, carrying out investigations, escorting criminals to court or to an airport in case of an extradition.