Army bomb disposal experts were called in after two of the three incidents, which took place within two hours of each other on Friday night.

No-one was injured during the explosions, although a number of cars and a phone box were damaged.

On Saturday Merseyside Police said it is believed the attacks were random and carried out by youths.

We're very concerned about youths running round throwing fireworks Inspector Bob Johnson, Merseyside Police

In the first incident, at 1955 BST on Larkhill Lane, Clubmoor, two youths were seen throwing a brick then a firework through the window of a blue Vauxhall Astra.

About an hour later bomb disposal teams were called in after the explosion in a phone box, in Middlemass Hey, Netherley, which caused damage to nearby cars.

Less than 30 minutes later, at 2120 BST, the windows of a Ford Focus car were blown out in Holland Street, Kensington, and again bomb disposal teams attended.

Inspector Bob Johnson, of Merseyside Police, said the attacks are not thought to have been planned, and after searching the areas of the explosions the bomb disposal teams found no suspect devices.

'Organised displays'

He told BBC News Online: "These attacks are very likely to have been carried out by youths and they are not some gang-related acts.

"No-one was injured but there was considerable damage caused."

"I would urge parents to be aware of what they're children are doing and stop them getting hold of fireworks," he said.

"Liverpool provides a good few organised firework displays, and we have no problems with properly supervised family displays, but we're very concerned about youths running round throwing fireworks."