The company which animal rights group Speak claimed to be the contractor building Oxford University's new animal research lab has categorically denied any involvement.
Mace Plus Ltd refuted claims published on the Speak website that it had been contracted to build the £20m research facility in South Parks Road.
Mace is involved in building work for swimming at the 2012 Olympics and Speak threatened it might target its Games' operation.
But a spokesman for umbrella company Mace Ltd said last night the firm had nothing to do with the construction of the laboratory.
In a statement it said: "Neither Mace Ltd nor any of its sub companies are involved in the construction of the animal laboratory, as stated in June 2006 to Construction News.
"Mace pulled out of this scheme in 2004. Oxford University is an important client and works closely with both Mace Ltd and Mace Plus Ltd."
The company said it was involved in other Oxford University projects, but not the animal lab.
A spokeswoman for Oxford University added: "Anybody who is named in connection with this project, whether or not it is true, is at risk of becoming a target for extremists.
"Our strict policy is that we will not confirm any such details, and we regard it as highly irresponsible and potentially dangerous for this sort of information to be published."
On its website, Speak threatened to target the construction firm, which it claimed was a "key company" involved in building the animal lab.
Speak spokesman Robert Cogswell added: "We are also aware that Mace Ltd are part of a consortium to build the London Olympic Games project. We will of course be scrutinising the details of their involvement and we have neither ruled in nor ruled out including the Olympic project in our overall strategy."