Brighton and Hove City Council have described Sunday's proposed demonstration as "irresponsible".

The entrance to the undercliff walk has been blocked with secure fencing for several months pending a plan to stabilise the cliffs.

However, the plans were delayed after objections from English Nature.

Criminal prosecution

A decision is expected in the near future after the issue was called in for a public inquiry. Until then the walk is indefinitely closed.

Cllr Gill Mitchell said: "The council has done everything possible to come up with a solution that is both sensitive to the historic importance of the cliffs and that would prevent further falls of chalk.

"But we have been prevented from carrying out the work.

"Those behind the mass trespass are being irresponsible and risking not only their own personal safety, but the safety of their partners, friends and families solely for the purpose of making a point.

"I would urge them to reconsider."

The council warned that anyone damaging the fencing blocking off the undercliff walk could face criminal prosecution.