Squatters inside a former power station owned by Oxford University are at risk of being hit by falling masonry, the institution has warned.
The group, known as Iffley Open House, took over a car showroom owned by Wadham College but left after being told to move out.
However, on Sunday, 25 people claimed squatters' rights in The Old Power Station owned by Said Business School.
The university is now seeking a possession order on the building.
It is in the process of developing the site in Osney, west of the city centre, and insists it will not be safe until refurbishments are completed.
Ten volunteers are thought to be working with the homeless people.
The university has been using part of the building to store thousands of items from the Museum of the History of Science and the Pitt Rivers Museum.
It said: "For some time, we have prevented our staff from entering the part of the building which has been occupied by Iffley Open House because of a number of safety concerns, including the risk of falling masonry.
"We will therefore be seeking an interim possession order as soon as possible, out of concern for the safety of the members... we are very sympathetic to the plight of these homeless people who need somewhere safe to live and we will continue to speak to their representatives about how to resolve the situation."
A spokesman for the group, Neo, said: "It's a shame, it would've been nice to spend the rest of winter here.
"It's a nice place. It's quite a strong building. I haven't seen any evidence of falling masonry… it's a good excuse for getting us out."
Ambulances descended on the building earlier this month when a man became ill after handling toxic seeds, which some exhibits contain.