A green lobby led by top Cambridge dons could next week scupper plans for a new Cambridge college.
The dons want the university to reverse its decision to build on ancient meadows on the city's margins.
The university has won city council approval for removing from the protected green belt the so-called "19-acre field" site in west Cambridge. Now part of the university farm, the rural setting is thought to be an ideal location for a new college.
David Todd-Jones, director of estate management, referring to the benefactor of Robinson College, said: "If there were another Robinson who could provide the money for a fully endowed college, I can't believe the university would say no."
But some of the university's leading academics are set to protest at the plans next week in an emergency meeting of Regent's House, the dons' parliament.
Richard Grove, environmental historian, said: "The university should be setting an example as a protector of the environment. As it is, the university is emerging as a threat to the environment of Cambridgeshire."
Several leading scientists have signed the petition calling for the meeting, including Richard Ellis, director of the Institute of Astronomy, and Ian McCave, head of the earth sciences department. There are fears that additional light and vibration prompted by increased development could affect telescopes and seismic equipment sited nearby.
For the university, Mr Todd-Jones said: "It is quite ridiculous to suggest that the university is trying to grab as much green-belt land as possible." He pointed out that the site had been offered "as part compensation" to the university after a Government inspector had rejected plans to remove from the green belt the so-called "rifle range" site near the city centre.
He added that the overall plans represent "a green belt gain" because the site is smaller than the rifle range and ancillary land by some 15 hectares.
But Dr Grove, founder of the Cambridge Green Belt Campaign pressure group, said there was "no fair exchange" because the 19-acre field site is "ancient meadow land" whereas the rifle range is "semi-urban land".
He has been backed by Ian Nicol, chairman of Cambridgeshire's Council for the Protection of Rural England and fellow of Fitzwilliam College. He said: "The university is already too big. There must be a limit to the expansion."