The head of pharmacology at Milan's state university says a weekend break-in by animal rights activists who freed about 100 laboratory animals has cost years of research and hundreds of thousands of euros (dollars) in damage.

Prof. Francesco Scaglione said Tuesday the activists also mixed up cages, making it impossible to continue some experiments. Scaglione said most of the research is seeking treatments for brain diseases like Parkinson's, Alzheimer's and dementia.

Five animal rights activists who occupied the lab Saturday released about 100 of the 800 animals, mostly mice, while animal activists and lab supporters both demonstrated outside. Scaglione said his department plans to press charges for theft and trespassing, and to recover financial damages.

The activists said in a website post that their goal was to free the animals.