PROTESTERS are planning a prolonged campaign of direct action to hit the construction of Oxford's new Westgate Centre.

The spectre of building work being halted by demonstrations was raised, as opponents of the £300m shopping scheme vowed to step up the pressure on the developers.

With construction of the Westgate expected to take three years, protesters threatened to hound the developers "right to the end".

Tree occupations and protests to stop the removal of trees near the Westgate car park last month resulted in arrests and security guards being called in.

But there is now a serious risk of a sustained campaign of direct action disrupting demolition and building work as vast amounts of materials and equipment move to and from the site.

Protesters attending a Town Hall meeting said that they had agreed to embrace direct action as a weapon "to force the company behind the scheme to realise that there is a serious and substantial opposition to it".

One local business group immediately warned that mass protests could prolong building work by months, with a devastating impact on other retailers and jobs.

Julia Gasper, of the Oxford Against Westgate group, said: "We want to see peaceful but assertive demonstrations to gain public attention.

"I have heard people talking about going further, if peaceful or legal protests do not work. I certainly do not want to see any violence or anyone getting hurt. But people are angry and there is a degree of frustration with the democratic process.

"The people of Oxford own the land on which the Westgate shopping centre stands. It doesn't belong to the council. The city council has abused our trust and it is time for us to reassert our ownership of the site in question."

Construction work is due to get under way this summer and will continue until the autumn of 2011.

One campaigner, involved in the tree protests, warned the Westgate construction could become "messy" if developers did not pull back from "an environmental disaster".

With the results of a public inquiry into proposed demolition of homes in Abbey Place still awaited, campaigners say the possibility of further legal challenges should also be investigated.

Ms Gasper, a writer who will be contesting the city council Quarry ward for UKIP in the May elections, said: "Ideally, some vulnerable individual should bring a prosecution on the grounds that their health or their housing rights have been violated. Since the scheme breaches so many legal limits and guidelines for pollution and flood risk, it must be challenged in the courts."

Sushila Dhall, the ward councillor for Carfax, who spoke at the Town Hall meeting, said: "As a councillor I cannot condone illegal action. But I do have sympathy with those talking about direct action.

"I understand why they are doing that. Direct action can have a big impact, if it is intelligent and non-violent."

Graham Jones, of ROX (Rescue Oxford), said: "It would be cause for great regret if this happened. The work which is going to last three-and-a-half years is going to be disruptive enough in any case.

"If protests extended it for six months or even longer it would inflict terrible damage not just on Westgate but the whole city."

Campaigners fighting the shopping centre also agreed to launch a postal campaign targeting John Lewis, the flagship store in the development already approved by the city council. They called for shoppers to boycott the new centre when it opens in 2011. The protest group also called on residents in the May elections to vote out councillors who backed the scheme.

Simon Ward, spokesman for The Westgate Partnership, said the protesters' fears over increased car journeys and congestion were misplaced.