The controversial new animal research facility in Oxford has opened in secret with hundreds of mice moved to the completed building last week, it was revealed today.

The University of Oxford said the process of rehousing thousands of animals - including monkeys, mice, rats, hamsters, gerbils, fish, frogs and ferrets - into its new Biomedical Sciences Building would take until the middle of next year.

Officials told a press conference in London that construction of the new facility, in South Parks Road, had been finished after a two-year delay following an “unlawful campaign of intimidation” by animal rights fanatics.

The security costs of constructing and now running the building as an animal research lab were not yet known, the university officials admitted.

However, they said the Government had agreed to pick up the tab for everything but the “core” cost of the development.

University Registrar Julie Maxton said: “The Biomedical Sciences Building is now complete and the first mice moved into the building last week. The animal migration will take several months, and it will not be fully operational until 2009.

“It aims to provide new advances in life saving medicine and we will only be using animals when no other technique can be used.”

Dr Maxton said once fully operational the Biomedical Sciences Building would support medical research into many “conditions of concern”, including HIV, stroke, heart attacks, diabetes, Alzheimer’s and Parkinson’s.

The building, in the science area of the University, was built to rehouse research animals currently held in older buildings scattered throughout the area.

Officials said there would be no increase in animals used by the university and 98 per cent of the animals held would be rodents - mostly mice. All the animals used in the experiments are eventually killed.

Dr Maxton, explaining the delays in completing the development, said: “We had to face not only legitimate and lawful protest but also a wholly unacceptable and unlawful campaign of intimidation and violence. We are pleased to get to this stage but there is no sense of triumphalism.”

The University, in a statement, stressed it would not describe the completion of the building as a “victory against extremism” because it “never sought a battle”.

It said: “Our aim was very simple - to move animals used in medical research into facilities that would be better for those animals”.

It said it had “always acknowledged and supported” people’s right to protest and to express their views within the law.

The University refused to give out details of security measures put in place to protect the building but said safety concerns had been a “major consideration” in its design and construction.

It added: “We believe the security planning we have in place will allow the building to function as a normal research facility, albeit one with careful security measures.”

Building work started on the facility in autumn 2003, but was halted in 2004 for 16 months following acts of criminal damage against “alleged” contractors and suppliers.

In November 2004, the University obtained an injunction against animal rights protesters aimed at protecting University members and contractors and placing an exclusion zone around the building while allowing weekly demonstrations in front of it.

The University said further criminal acts had taken place in the summer of 2005, and in 2006 and 2007.