By Jonathan Amos
BBC News Online science staff
Cambridge University has conceded its controversial primate laboratory may never be built because of high costs.
The work will be done on marmosets and macaques
The UK Government approved plans for the £30m neuroscience centre on Friday, to the dismay of animal rights groups who say the lab's work will be cruel.
But Cambridge Pro-Vice-Chancellor Tony Minson said a £7m shortfall in funding would mean construction work next year would be delayed - and may never begin.
"Unless we find a business plan that works, the project is at risk," he said.
The lab, earmarked for university land on the northern outskirts of the city, will conduct brain experiments on marmosets and macaques, to advance the understanding and treatment of neurological disorders, such as Parkinson's and Alzheimer's disease.
Local planners had previously thrown out the university's request to build the lab after police raised fears about public safety at the site, on a main road and close to a motorway intersection.
But after the direct intervention of Tony Blair and his chief scientific adviser, Sir David King, in support of the lab, a public inquiry was held late last year and its final decision called into Whitehall for approval.
On Friday, Mr Prescott's office said the inspector recommended that the university's appeal be dismissed but Mr Prescott disagreed.
"...the Secretary of State concludes that in the circumstances of this case very special circumstances exist that are sufficient to outweigh any harm to the Green Belt and other interests caused by the development," a spokesperson said.
Cambridge University said it was pleased the research centre had been given the go-ahead, but accepted increased costs had put a big question mark against the lab's future.
"It's conceivable it may not go ahead," Professor Minson said. "We're convinced of the science; we're convinced of its national importance - and so is the Deputy Prime Minister. If we can manage the finances, we will do it."
Professor Minson said it was the expected running costs of £1.5m a year that were proving particularly problematic.
Animal rights groups condemned Friday's decision. They said the science was flawed because the monkey and human brains differed in vital respects, making many experiments worthless.
They also questioned the university's record on animal welfare, arguing recent undercover work had revealed poor practice in the university's other labs.
Wendy Higgins, from the British Union for the Abolition of Vivisection (Buav), said the decision was no surprise, coming "just at the time that Cambridge University itself is throwing doubt over the project due to rising costs.
"This means the government has kept its bargain to back up the vivisection industry by granting approval in the full knowledge that the final decision is now left to the university."
The Buav predicted that, if the project went ahead, it would be blighted at every step by animal rights protests.
"With such a display of arrogant disregard for public opinion, is it any wonder that an increasing number of citizens feel their only option is to abandon the political process and take to the streets instead?" Higgins said.
The fuss over the project and the university's concern over finances have led to wide speculation among campaign groups that Cambridge, now that it has its "victory", will withdraw its application - with the government moving primate study to its military research centre at Porton Down, in Wiltshire.
"Cambridge is looking for a way out," said Andrew Tyler, the director of Animal Aid. "If they take it to Porton Down it will compound the fact that this is grotesque and pointless research by making it secret and inaccessible as well. Wherever it goes, we will fight it."
Primates represent a very small part of the animal experimentation programme in Britain. The vast majority of 2.7 million annual procedures are done on rodents.
Fewer than 3,500 experiments are carried out on mokeys, and fewer still involve a highly invasive practice such as cutting into the brain.
Professor Chris Higgins, director of the Medical Research Council's Clinical Sciences Centre, said: "Our work on basic brain function couldn't be applied to human disease without some sort of research being done on animals - and in some cases, these animals have to be primates.
"The human brain is clearly more complex than a mouse's, so problems such as memory degeneration have to be studied in the brain of an animal that has the same level of memory functions as a human being."
The decision was also welcomed by the Parkinson's Disease Society.
"Improved treatment and the search for a cure depend crucially on a better understanding of the processes of the disease," a spokesperson said.
"In the last few decades thousands of people with Parkinson's have benefited from new therapies, such as L-Dopa, which would not have been developed but for the insights gained from research involving animals."