Revival MP Petar Petrov told reporters in parliament's corridors that the party has asked interior minister Ivan Demerdzhiev and acting interior ministry chief secretary Lyubomir Nikolov to answer MPs' questions over the killing of Botev Plovdiv football club president Iliyan Filipov.

Revival wants the hearing held tomorrow, at a meeting of parliament's committee on internal security and public order.

"We think it's important to find out how the interior ministry is organized when it comes to solving this crime quickly, and to preventing crimes like it," Petrov said.

Petrov called the case a worrying sign, made worse by the political climate and the start of the election campaign. He said Bulgaria could slide back to the past, even though prime minister Rumen Radev has said the fight against oligarchy is over.

"This has even changed parliament's agenda," Petrov added.

Hours earlier, Plovdiv district prosecutors said they were overseeing a pre-trial investigation into the deliberate killing of a Plovdiv businessman identified only by the initials I.F. Botev Plovdiv's management later confirmed the victim was Iliyan Filipov.