Winchester is again bracing itself to be an environmental battleground as the county council prepares to finally start work on its controversial park-and-ride extension.

Contractors are moving on to the site at Bar End to build a compound in readiness for work on the new 400-plus car park on the former bypass.

Campaigners have delayed the project for nearly five years and predict that eco-warriors will disrupt work due to start on Monday.

The land, formerly the A33 bypass, was dug up and returned to nature as compensation for the loss of Twyford Down to the M3 in the early 1990s.

The Winchester Meadows Conservation Alliance said many environmental activists viewed the park-and-ride plan as a betrayal.

Keith Story, the alliance chairman, said there was still a possibility of last-minute legal action but is was growing unlikely.

He said: "We are not officially abandoning our lawful campaign to save the meadows, but we are having to accept the possibility of defeat.

"I do expect to see the eco-warriors. I would be surprised if they did not take an interest in this piece of environmental vandalism."

The Twyford Down campaign from 1992-94 was the catalyst for the anti-roads movement which saw the government drop its road-building programme. A county council spokesman said: "The site will be secured. We are not putting a fence up around the site to keep people out. It is for health and safety reasons.

"It will take a few days to set up the site. We are aiming to start as soon as we can. Building work by Mildren Construction Ltd will take four months. The police have been notified and they are aware of the situation. A protest meeting has been called for this Sunday between 11am and 1pm. TV naturalist David Bellamy has said he will attend.

Meanwhile, Mr Story, along with Alan Weeks, chairman of the Winchester City Residents' Association, and former city councillor David Croker, met Winchester detectives to discuss their allegation of public misconduct by county council officers. Mr Story presented a new 40-page dossier and has named informants who gave him information in confidence.

Mr Story said: "They understand that and they accept that."