Two major developments off Oxford's ring road could feature a new centre for the emergency services, a business park and hundreds of new homes.

One of the schemes would see a bridge built over the A40 as part of a scheme that would see 800 to 1,200 new homes built as an extension of the Barton estate.

On the other side of Oxford, there are plans to create a 'northern gateway' for the city on college-owned land near the Pear Tree roundabout.

It is hoped the site will provide a new base for police, ambulance and fire services, with a a hotel and research centre creating hundreds of new jobs.

Details of the two multi-million-pound schemes are set out in city's new planning blueprint, which earmarks key development sites.

A consortium is soon to be formed to develop the parcel of land at Pear Tree between the A40 and the A44, which is largely owned by St John's and Worcester colleges.

One of the companies involved, Goodman, the international property group, owns the Oxford Business Park, in Cowley, which is moving towards completion.

Talks have been held with all the three main emergency services about relocating their city-centre bases.

It is hoped that operating on a site next to the county's main trunk roads would significantly reduce emergency response times.

The move would free up the Oxford police headquarters in St Aldate's, which would be replaced by a smaller city centre base, and also the fire service base in Rewley Road.

Oxford City Council says it will shortly begin work on a 'Northern Gateway Action Plan', which will carry out detailed assessment of the site and see how the scheme's impact on the congested A34 and A40 can be minimised.

It will also examine whether pockets of land need to be released from the Green Belt, with a "highly focused" Green Belt boundary review proposed.

The Barton scheme would see at least 800 homes built north of the ring road. A bridge over the A40 would offer bus, cycle and pedestrian access into Northway and Headington.

Mark Jaggard, the city council's planning policy manager, said: "Barton has always been landlocked by the ring road. This would integrate it with the Headington area."

He said the development would act as a "catalyst for the regeneration of Barton and Northway", with new facilities and thousands of new residents helping sustain existing shops and services.

The city council report concludes traffic problems would be eased by highway improvements proposed by the county council as part of its Access to Oxford package.

Kevin Dixon, of Keir Property, the other company involved in the 'northern gateway' project, said he hoped a consortium would shortly be created to take the plans forward.

But with the city council already committed to a Green Belt review to allow 4,000 homes to be built near Grenoble Road, Oxford Preservation Trust expressed concern.

Debbie Dance, the trust's director, said: "It seems extraordinary that this piecemeal approach to the Green Belt is taking place.

"Quite what has happened to the permanence of the Green Belt, we don't know. To see bits and pieces being cherry picked out without any thought to the precedent being set for other areas cannot be right for planning Oxford's future."