British council officials in Basildon, Essex, today ordered Travellers to leave Dale Farm by September 19th or be forcibly evicted.
The notice follows a decade-long row over unauthorised properties on the former scrap yard.
Although half the site is legal, more than 80 properties have no planning permission, and about 400 people are said to be living there illegally.
Travellers and supporters have promised to resist eviction without violence, but police have begun preparations for major disorder.
Speaking in the House of Commons today, Local Government Secretary Eric Pickles said planning rules would be enforced equally to travellers and settled residents, as the row over the break-up of Britain's largest illegal settlement intensified.
"The planning rules must be blind towards someone's ethnic background," he said.
"It's right and proper that we should respect the lifestyle choices of the Travelling community, but this does not give them particular rights over other citizens, particularly in the settled community."