Oxford University has refused to say when its controversial animal experiment laboratory will finally open - or how much over budget the project has run.

The university has met a series of questions put by the Oxford Mail in relation to the £20m project in South Parks Road, which was due to open at the end of 2005, with a wall of silence.

It said answering questions in relation to the laboratory posed a "security risk".

We asked: How far behind schedule the project was How much it was over budget How much had been spent by the university on security measures What security measures would be in place when the lab opened, and When the facility was due to open.

After a 16-month delay, brought on by a series of threats of intimidation and violence, building work restarted at the end of 2005, but the project is still not finished.

University spokesman Ruth Collier said they had been advised that giving out any information about the lab could pose a threat to the security of the project.

She added: "We have to operate within the constraints of the security advice we are given."

The laboratory has been the target of anti-vivisection campaigners, both peaceful and violent who are intent on forcing the university to halt its work.

Oxford University Chancellor Chris Patten has vowed the institution will not bow to extremists .

He said the lab would open in the interests of medical science.

Robert Cogswell, a spokesman for the non-violent animal rights campaign group Speak, said: "Not surprisingly, Oxford University has refused to discuss any details concerning the lab.

"This has less to do with security and more to do with their continuing attempts to hoodwink the public.

"From the very start of this project, the university has indulged in a campaign of deceit and misinformation.

"It's important that people look at the facts and draw their own conclusions.

"Speak will be around for a long time to come and we will continue to campaign within a legal framework.

"This battle is far from over, the laboratory isn't even completed yet and they still have to run it after it's built.

"Oxford University has thrown everything they have at a small campaigning group and we're still full of fight.

"Speak is in this for the long term."