A leading medical research company has backed out of plans to buy a former school site in Bradford.

Nektar Therapeutics - which has changed its name from Bradford Particle Design - vowed in November it would still forge ahead and take over Nab Wood Middle School despite a fire at the building.

Now residents' group Nab Wood Together is calling on owner Bradford Council to demolish the school amid fears the vacant building will attract vandals.

"The site is open - and even before the fire there were windows smashed and graffiti," said the residents' group treasurer Shanti Thakker.

"We're so disappointed the company has decided not to buy the site and hope another buyer comes forward very soon."

The firm, based at Listerhills Science Park, in Campus Road, had planned to demolish the New Close Road school to make way for a new car park and building which would be used for small-scale research and administration.

But managing director Gwyn Humphries said he was sorry plans had changed. "It is the result of a budget review and strategic review with our parent company in California," he said, "They are investing a lot of money in the company. We are really sorry the purchase could not go ahead. It would have been ideal if we could hang on to the site, but we could not say how long for.

"We will continue to expand but not as quickly as we thought."

The five-hour fire in November destroyed a fifth of the building, after which the Council demolished a section of the school and fenced off the site.

A Bradford Council Management spokesman said: "The fact that Nektar Therapeutics is pulling out of buying the site will be reported to the next School Site Disposal Committee meeting in mid-February at which we will be recommending that the Council proceeds with another bidder for the property.

"It is likely that the building itself will eventually be demolished.