Colleagues of the the journalist raped and murdered in a Bulgarian park last week have called for an independent investigation into her death amid fears she may have been targeted because of her reporting on alleged corruption.

Victoria Marinova, a presenter and director at a local television station, was found murdered in a park in Ruse, a town on the Danube on the country's northern border, on Saturday. She had been beaten, raped, and strangled.

Bulgarian police have said they are examining all possible motives for the killing, including the possibility that it was linked to her work.

But investigative reporters who worked with her on her last report said they feared authorities were trying to "hide something" and warned it would be premature to rule out a motive connected with her work.