An NELC spokesperson said: "The council took immediate action to try to prevent further unauthorised use of the car park and are asking the group to leave the land immediately.
"The council has also started legal proceedings to have the travellers removed.
"The gates to the car parks, off Kings Road, will be closed overnight from 7pm. Our advice would be not to use the car park which the travellers are occupying."
A public notice posted at the site also bars the travellers from returning for three months.
Under new rules launched under a Government crackdown late last month, travellers can receive a hefty fine of up to £20,000 if they set up illegal camps. The move aims to prevent lengthy legal battles like that over the Dale Farm gypsy camp in Crays Hill, Essex, which was occupied for ten years before evictions in 2011.