Council officials let travellers into a popular city park – even unlocking the gates put there to keep them out.

Now, the local authority must go through the courts for a possession order to evict the travellers, which will take days and potentially cost the taxpayer thousands of pounds.

When the group of about 20 vehicles first arrived at Wild Park, Brighton, they were greeted by a recently installed padlocked entrance.

But, determined to access the popular open space, members of the encampment were repeatedly driving over pavements and artificial mounds intended to keep travellers out.

To reduce the risk to everyone, confidential emails seen by The Argus confirm officials at Brighton and Hove City Council decided to open the locked gate.

Police officers have said the decision meant powers to legally evict the group straight away had disappeared.

Conservative councillor Dawn Barnett said: “All the council is doing is encouraging unauthorised encampments.

“I think it’s not only health and safety gone mad, I think the council is mad for doing it.” Colin Bradford, who runs the annual Wild Park Family Fun Day, said: “It’s not acceptable.

“It’s a public park and people want to use it. It’s supposed to be there for everybody.” The group arrived at the site on Friday evening.

A confidential email sent by the local authority to councillors said: “After the initial trespass was reported, Sussex Police highlighted the dangerous nature with which the group were accessing the field, as the main access gate was locked following previous enforcement action.

“As such a decision was taken to open the access gate in order to reduce the risk to road users and to stop the occupants from crossing the pavement to access the road.”

Inspector Bill Whitehead, of Sussex Police, said a Section 61 order for an immediate eviction could have been granted if the gate had remained closed.

This was on the grounds that there was a “danger to the travellers and others”.

He added the local authority’s decision to open up access had meant these powers had now disappeared.

Insp Whitehead said there was a “need to balance all the communities affected” when dealing with issues of unauthorised encampments.

He added: “It’s a huge park and 95% of it is still available for other people to use.”

But Michael Murray, of Brighton and Hove Environmental Action Group, said: “The Section 61 order is intended to stop the council from spending vast amounts of money on evicting groups.

“As it is, the system is an absurd bureaucratic merry-go-round.”

Following a request made under the Freedom of Information Act, the council said there was no specific budget set aside for repairs to gates, locks, re-turfing, and artificial mounds.

However, the council said its traveller budget for this year was about £520,000.

Earlier this year, The Argus reported that the local authority spent £200,000 on unauthorised encampments across the city in 2012/13.

This included £150,000 on rubbish collection, providing facilities and removing vehicles from unauthorised encampments.

Geoff Raw, an executive director at the council, said: "After the encampment had arrived the gate was opened with council officers and police present as a measure to avoid danger to road users. This has been done before and all enforcement options are being kept under review. The council has started eviction proceedings against this group, and there is a court hearing next Wednesday."