Two of Oxford University's most prestigious colleges have called for an end to the "vandalism" of the historic High Street by transport planners.

All Souls and University colleges claim one of Europe's most beautiful streets is being ruined by pollution, noise and clutter, resulting from "ill-thought out" bus policies.

The attack was prompted by news that Oxfordshire County Council wants to put more bus stops in the street.

But the colleges said more buses would spoil views of the medieval college buildings, while condemning students to endure "24-hour-a-day bus noise and air pollution".

All Souls' bursar Thomas Seaman said the effect of two bus stops in front of the college's main entrance was "too appalling to contemplate".

He said: "A nearly 600-year-old gateway will be hidden by hideous street signage, buses stopping and starting their journeys 24 hours a day, with attendant groups of passengers waiting.

"We have maintained our presence on the High Street for 580 years, contributing to the reputation and fortune of Oxford over that time.

"We employ over 100 people, all local residents. What is our reward? A thoughtless proposal from engineers who have studied maps, not organisations or people, who seem to think improving bus passengers' travel experience trumps the damage they might be doing to the environment and to the enterprises which comprise this city's very life blood."

University College domestic bursar Elizabeth Crawford said: "Increased numbers of bus stops will inevitably mean more buses.

"You may be interested to know that pollution levels in Oxford feature in questions on A-Level geography papers, because they are so closely comparable to those in Mexico City and Beijing.

"The High Street has already become a sorry sight in terms of signage, street furniture and street layout, and your proposal will simply make it into a bus station."

The warden of All Souls, Dr John Davis, said the college was also concerned about a pollution control monitor - among what he called "eyesore boxes and machines" - in the street. He said the college was told five years ago that the monitor was a temporary measure.

Graham Jones, of the Oxford High Street Business Association, said businesses were upset the council seemed bent on pushing through its plans without sufficient consultation.

But Ian Hudspeth, the council's cabinet member for transport, said: "The proposals were sent out to colleges and businesses to get some feedback from them and see whether they agree.

"It's important to highlight that we want to work with them, not against them."