Police have received a complaint from the major, attached to Army intelligence, about the incident at the car park of Jaic Hilton Hotel in Colombo, said police spokesman SSP Ajith Rohana.
According to the complaint, Malaka and the son of former minister Mano Wijeratne had assaulted the military officer and snatched his firearm, mobile phone and a gold chain.
Police said a driver of Malaka had later handed over the firearm to Slave Island police, saying he had found it in front of the hotel.
Police said Malaka will definitely be arrested in the coming days.
In the meantime, Malaka and his father Mervyn Silva were seen at Kelaniya Rajamaha Vihara, paying homage to the sacred Kapilawastu relics.
Hirunika Premachandra, the daughter of slain presidential advisor Bharatha Lakshman Premachandra, was also present.
Commenting on the assault incident, minister Silva has said that the police would do the needful and that he had more important matters to attend to.