A MOB of 100 boy racers caused chaos in a supermarket car park.

But police sent just two patrol cars and most fled when they arrived.

Only one man was issued with a formal warning.

The drivers swooped on the Asda car park in Blackwood as the store was still open.

Many customers were unable to get into the car park because of the sheer volume of traffic.

Shoppers also complained to store bosses and said they were intimidated by the anti-social behaviour.

Police issued a warning to a man from Aberdare for driving or acting in an anti-social manner.

If he is warned again, his car will be impounded and not released until a fee of £105 is paid.

Mark Wright, Asda spokesman, said: "This is something that is extremely concerning to us.

"We want to make sure that our stores provide a safe and comfortable manner to shop in.

"What happened on Thursday night is something we are not happy with and we want to make sure it is the first and last time it happens in Blackwood Asda . "The police took longer to turn up than we would have liked but I'm sure they did all they could do, as fast they could do it."

It is not known why so many drivers all arrived at the same time but many are known to pre-arrange meetings over the internet and by text message.

Police in Blackwood had promised to get tough on boy racers. It follows a series of incidents including one man who was prosecuted for 'car surfing' when he was spotted travelling on a car roof in the High Street.

Sergeant Lysha Williamson, of Blackwood police station, said: "Two cars attended at the scene which resulted in natural dispersal.

"Officers could only deal with the offences they could see.

"We are aware of the problems in Blackwood and Operation Sabre continues to run from Blackwood Police Station directly targeting anti-social driving in the area.

"CCTV systems have been used to positive effect in recent months and a number of prosecutions are still pending.

"We have recently seized two vehicles and will continue to seize cars if people persistently offend."

Blackwood councillor Kevin Etheridge believes police should seriously consider issuing a curfew in the town in order to disperse groups of youths congregating during the night-time.

He said: "The boy racers are running amok in the northern end of the town and it will soon become a no-go area."