20 nails inside Mongkok bomb

The home-made bomb detonated by police in a Mongkok shopping centre on Tuesday night contained about 20 nails.

Bomb disposal expert Chow Shek-kin said yesterday his team was trying to reconstruct the bomb and check how it worked.

The device, containing a clock, nails and battery, was hidden in a cardboard box, outside a men's toilet on the first-floor of Ho King Commercial Centre.

Chief Inspector Matthew Kwok Ho-fai from Kowloon West Regional Crime Unit said there had been no blackmail threat or demand for money.

The device was discovered at 9pm on Tuesday after an anonymous call to police.

The scare came just a week after a woman was hurt in a bomb blast at Tuen Mun's Jusco department store.