Hundreds of placard-waving protesters are to hold a demonstration in Bristol to object to plans by developers to build 10,000 new homes on green belt land on the outskirts of the city.

Members of the Dundry Residents Action Group (DRAG) are to join forces with other campaign groups across the Bristol area to hold a protest outside the Architectural Centre on the city's harbourside on March 7, where the plans have gone on display.

Developer LandTrust revealed plans this week to build thousands of new homes on hundreds of acres of green belt land between A38 at Dundry, near the Barrow Tanks, right down to the A370 Long Ashton bypass.

The proposed new development, expected to cost about £2.5 billion, would be called Ashton Park.

Campaigners say they are angry that plans have been put forward when the blueprint for the South West Regional Spatial Strategy (RSS) has not been agreed.

The RSS was launched last year in response to a Government directive which said thousands of new homes needed to be built across the South West to cope with the growing population. The strategy, led by the Regional Assembly, identified the swathe of green belt land on the slopes of Dundry and Ashton Vale as a potential area for growth.

A consultation on the RSS got under way last year, with more than 35,000 responses received. A final decision on the RSS and whether the land can be used for any new development is not expected until August.

DRAG spokeswoman Debbie Nicholls said campaigners were angry developers had put forward plans when a decision on whether the land could be used has yet to be made.

Mrs Nicholls said: "These developers are moving ahead and planning this urban extension regardless of the outcome of the RSS.

"They have no right to be putting forward plans for green belt land which is currently protected.

"Once developers have permission, they can put it in their pocket and start work when it suits them.

"No one has the right to build on green belt and this protected land should only ever be used in exceptional circumstances.

"The demonstration will be a peaceful one, but we want to make it clear to the developers the strength of feeling against these plans.

"We are not going to roll over and give in and plan to fight to the end."

A period of consultation on the plans begins officially today and LandTrust is already talking to Bristol City Council and North Somerset Council about the details of the scheme.

Ashton Park will straddle the local authority border and both sets of planners will have their say when an outline planning application goes in this summer.

A joint local councils group, made up of representatives from Barrow Gurney, Long Ashton and Dundry, has also been formed to campaign against the development.

Barrow Gurney Parish Council chairman Geoff Coombes said: "We strongly oppose this development and our main role is to defend the green belt. It is also vital that the separate identities of the local villages are retained and they are not swallowed up in this mass of new housing."

LandTrust's proposals also show a new link road between the A370 and A38, which would provide the new bypass for the village which Barrow Gurney residents have been campaigning for.

Councillor Coombes said: "This bypass is needed to cope with the existing problems with the large amount of traffic travelling through the village, not just for this development."

North Somerset Council is also objecting to the RSS blueprint on the basis the scale of development is too large. The Ashton Park development, which will bring a further 25,000 people to the area, will have a secondary school, five primary schools, two district centres with a number of shops, including a food store, a community centre and a business park.

As well as the thousands of construction jobs involved in creating the new town, there will be about 7,000 permanent jobs for local people, about half in the shops, schools and other facilities and the rest at the business park.

Two other major features of the project are the creation of a new high-speed bus link with the city centre – and hundreds of acres of parkland, including water features and a green corridor through the whole developmen.

It is hoped that eventually this link will be extended out to Bristol International Airport.

If the development gets the green light, it will not be complete for perhaps another 20 years, but work on the first homes and the infrastructure – roads, drains, schools, shops, libraries – should start next year. The first residents could be moving in from 2011 and the different neighbourhoods are expected to spring up over the next two decades as various developers embark on their parts of the project.

The housing will include flats, three and four-bed family homes and an element of affordable housing.

Ashton Park would provide almost all the new housing proposed in the RSS for the area on the south-western edge of Bristol for the years up to 2026.