Thousands of Bosnians have demanded that authorities reinvestigate the deaths of a Muslim and a Serb, in a protest that bridged Bosnia's ethnic divide and called for an end to alleged state corruption and negligence.

Holding banners reading "Who is protecting the killers?" or "We want the truth," the protesters in Sarajevo on Tuesday accused authorities of covering up the killings of David Dragicevic and Dzenan Memic.

Memic, 22, from Sarajevo, died in 2016 in what prosecutors first said was murder, but later treated as a car crash. Two men have been charged with traffic violations, but Memic's father believes his son was murdered.

Dragicevic, 21, from Serb-held Banja Luka, was found dead in March. Police say he drowned, but Dragicevic's father also claims his son was killed.