Unlicensed fast-food sellers in London's royal parks are being targeted by tough new laws from Friday.

The new bill allows police to seize trolleys from "burger bandits" and increase the maximum penalty for illegal trading from £200 to £1,000.

While laws in the rest of London prevent illegal trading, the Royal Parks - which have their own regulations - are covered by legislation dating back to 1926 that does not permit the confiscation of equipment.

Areas around Buckingham Palace and St James's Park are particularly known for the stalls.

Arts Minister Alan Howarth, who published the bill, said: "These burger bandits ply a trade which is dirty, dangerous and disreputable.

"The illegal traders cheat visitors by charging exorbitant prices for food that has been prepared with no concern for food safety and hygiene, and which creates an environmental hazard for visitors and residents alike.

"Worse, there have been reports in the media that organised crime may be behind the traders' operations, with violence and intimidation an all-too-common feature of their activities.

"I am delighted that we can now look forward to a crackdown. Our royal parks should be safe and respectable places for everyone to enjoy."

Tom Corby, Royal Parks spokesman, said: "We are hoping that this is the beginning of the end for the burger bandits and their stinking trolleys. Their standards of food hygiene leave much to be desired and we do warn park users not to patronise them.

"We have posted notices in St James's Park where the illegal traders mostly congregate but these notices have been vandalised.

"Incredibly, there seems to be no shortage of customers willing to pay over the odds for their greasy and unsavoury wares."