Bulgarian police have detained a suspect in connection with the killing of investigative journalist Viktoria Marinova, whose body was found in a park in her hometown of Ruse four days ago, a government source familiar with the investigation told Reuters on Tuesday.

"We can say there is a suspect detained," the source said, declining to elaborate.

Ms Marinova's body was found in a park.

Her death was caused by blows to the head and suffocation, and her mobile phone, car keys, glasses and some of her clothing were missing.

An Interior Ministry spokeswoman declined to confirm or deny the information and said the ministry might issue a statement later on Tuesday.