A Conservative MP had rocks and tomatoes hurled at him after he was ambushed by around 50 "violent thugs" ahead of a talk on squatting, he said tonight.
Mike Weatherley, MP for Hove in East Sussex, had to seek refuge in a room as shouting protesters gathered outside at the University of Sussex near Brighton.
He had been invited to talk about his involvement in changing the law to criminalise squatting.
But just before the debate was to start, a large mob of non-students surrounded him and threatened him, he said.
Security officials barricaded him and his staff in a room until the police arrived and took him away in a van.
Mr Weatherley said: "It's absolutely outrageous that a peaceful event such as this should be hijacked by a group of violent thugs.
"As soon as I walked into the lecture theatre someone attempted to punch me.
"The event was immediately abandoned, but as we tried to leave, rocks were hurled, and two female members of my staff were injured.
"My staff and I were barricaded into a room, until the police arrived."
Mr Weatherley has been campaigning for squatting to be criminalised since his election to Parliament in 2010.
Sussex Police said: "Just before 1.50pm on Wednesday 14 November, police were called to the Silverstone Building in Arts Road on the University of Sussex campus at Falmer, after a report of a disturbance.
"A group of people were outside the building where Mike Weatherley MP was present.
"Officers took Mr Weatherley to safety in a police van.
"It is understood that there are no reports of injury at this time."
One member of Mr Weatherley's staff had her arm crushed in a door while another had a rock thrown at her neck, it was claimed.
Mr Weatherley said they were "very fortunate" to have found a room to lock themselves in, away from the crowd.
He voiced his thanks to the security guards and the police whom he has made a statement to about the incident, which follows opposition from pro-squatting campaigners against the introduction of new laws.
Powers which came into effect on September 1 allow local authorities to call in the police to arrest squatters, rather than pursuing lengthy civil eviction proceedings through the courts.
Under the powers, contained in the Legal Aid, Sentencing and Punishment of Offenders Act 2012, councils can remove squatters by simply complaining to the police who, if satisfied that the claim is genuine, can arrest the illegal tenants.
Mr Weatherley said: "The squatters have regularly attempted to stop free speech from taking place for the precise reason that they cannot justify their criminal behaviour.
"I have made a statement to Sussex Police, and to Sussex University security, about the most violent members of the mob.
"Once the trouble started, both police and security did their jobs incredibly well. I am grateful to them."
The university said: "We are appalled to hear that Mike Weatherley was prevented from speaking on campus by a group of protestors. (They are) not our students."
A statement on the Squatters' Network of Brighton (And Hove Actually) website said: "All in all, an amazing day out!".
Part of it said: "Around 50-100 students, squatters and their supporters decided that they weren't going to let him speak.
"He'd barely walked on to campus before he was mobbed by a chanting crowd.
"His security and aides struggled to protect him as he fled, chased by a mob throwing eggs, tomatoes and other things.
"With no cops in sight, people were really showing their anger.
"Weatherley repeatedly shunned debate with any squatters before he criminalised us.
"This is the only time he has talked in public about squatting. People tried to let their voices be heard through the Government consultation on squatting, which came out as 90% opposed to banning squatting.
"This is why a broad range of people chased him off campus today.
"There were students, squatters, and supporters present."
Later, the University of Sussex said it was "appalled" by the incident which officials said did not involve their students.
In a statement, the university said: "We are appalled to hear that Mike Weatherley was prevented from speaking on campus by a group of protesters.
"We believe that the violent disruption was led by activist protesters from outside of the university, not by our students.
"We maintain a policy of freedom of speech on campus that is fundamental to the nature of academic institutions.
"It is a very positive aspect of British society that individuals responsible for important aspects of public life are willing to debate and discuss their actions and approaches.
"We successfully hold talks on campus from a wide range of people. Where protests have taken place in the past, they have been conducted in a peaceful way.
"We had appropriate security measures in place to protect our students and visitors as a matter of contingency, and we were able to put those into effect in this case.
"We are giving help and support to the police over the incident, and if there is any evidence of violent actions by our students we would of course provide that to them.
"We deeply regret that Mr Weatherley was not only unable to give his talk, depriving him and our students of any chance to discuss the issues concerned, but that he was prevented from doing so in such an aggressive manner.
"We also deeply regret the distress caused to Mr Weatherley and his staff as visitors to our campus, and the distress to our students who were involved in organising the talk."