Lebanese police officials say an operative with Lebanon's militant Hezbollah group was killed when a bomb he was holding went off in his home in the country's south.

The officials say it isn't clear what the operative, identified as Bilal Hassan, was doing with the bomb and now it got onto his home.

Initial reports were conflicting. Lebanon's private Al-Jadeed TV says Hassan was actually holding a grenade cartridge for a rocket-propelled-grenade launcher.

The state-run National News Agency said a "strange object" exploded in his house on the edge of the southern port-city of Sidon.

The officials spoke on condition of anonymity in line with regulations.

They said Hezbollah members inspected Hassan's house after the blast and were later followed by policemen who opened an investigation in the case.