Hong Kong police on Friday said they have reliable tips that protestors may use weapons that could cause serious injuries to the public.

The potential weapons that could be used at a mass rally Saturday include flammable powder that could cause explosions and drones to attack those on the ground.

The remarks came after an appeal board upheld police's decision to ban the planned rally over concerns of public safety.

During the police daily news conference, Kwok Pak-chung, regional commander of Hong Kong Island, revealed that protestors could use nail guns propelled by gunpowder and flash-bombs to create explosions.

The police will not rule out any level of force to counter such attacks, Kwok said, noting that gasoline bombs, corrosive liquid and air guns have been used to attack police officers at previous protests.

It was also revealed that fishing spears, bows and arrows, and stun guns might've been used during the now-banned mass rally on Saturday.