Avon and Somerset, Devon and Cornwall, Dorset, Gloucestershire and Wiltshire police forces have formed Operation Hartley to tackle the issue.

A spokesman said the intelligence-based project would run this summer, including during the Glastonbury Festival period at the end of June.

The operation will try to halt festivals organised for people without tickets for official events.

The spokesman said: "Around the time of the Glastonbury Festival, Avon and Somerset Police find people try to set up alternative festivals for people who don't have tickets.

"Operation Hartley sends out a clear message that these events will not be allowed and anybody who doesn't have a ticket for the Glastonbury Festival should stay away."