It is reported that the Narahenpita Police Station and the Colombo Crimes Division have commenced a special investigation into the incident.
Statements have been recorded in this regard from the security division of the hospital and several persons who had come for the construction work of the hospital.
A senior police spokesman told the Hiru News team, that an investigation has been launched into CCTV footage as well.
The grenade, which was designed to be activated with the help of a mosquito coil, was found in a rubbish bin in a toilet on the first floor of the hospital yesterday afternoon, according to hospital security sources.
However, it has not yet been revealed who brought it to the scene.
The grenade which was not in activated was handed over to the Bomb Disposal Unit of the Police Special Task Force for further investigations.