Fear of retribution by animal rights activists has led Oxford University to withhold information about the number of animal experiments it carried out last year.

Statistics released by the Home Office yesterday showed that nationally the number of experiments carried out on animals increased by 1.4 per cent to 2.9m in 2005.

But an Oxford University spokesman said: "We will not be releasing a breakdown of the figures because we are concerned about possible retribution from animal activists. Animal research in the university mirrors many of the national trends in the latest Home Office report such as the vast majority of research using rodents and fish, with mice being by far the largest group of animals used in research to help find possible treatments and cures for a wide range of diseases."

Meanwhile, police said they blocked Saturday's planned city centre animal rights protest because demonstrators failed to inform them of their plans in advance despite "repeated requests". Oxford police area commander Chief Supt David McWhirter, left, said: "Protesters were refusing to talk, therefore it was a reasonable assumption they may do something that could result in disruption to the life of the community.

"We have consistently said we will facilitate such demonstrations, which is part of the democratic rights of individuals within this country.

"However, this right to demonstrate is never a blank cheque."