Police clashed with demonstrators who tried to storm a Liberal Party debate at Sydney University being adjudicated by Education Minister Christopher Pyne last night.

Senators George Brandis and Mitch Fifield, along with Human Rights Commissioner Tim Wilson, were on the guest list for the John Howard Debating Cup at the university's St John's College.

At 7:00pm, about 45 minutes before Mr Pyne arrived, up to 30 protesters tried to enter the building but could not get in.

Police then arrived at the scene at which point there was a confrontation, described by ABC reporter Ben Worsley as "quite forceful", as a number of students were pushed to the ground.

Sorry, this video has expired Students clash with police at Sydney Uni

Footage from the scene also appears to show a police officer striking a student.

"Within two or three minutes a heavy police presence arrived, probably a couple of dozen police approached the protesters," Worsley said.

"A number of the protesters were pushed to the ground quite forcefully but the group has refused to leave."

About 50 police from the NSW Public Order and Riot Squad remained on the scene until after the debate finished.

Student Liberals condemn 'riot' outside debate

The protest appears to have been attended by members of the Socialist Alternative and the National Union of Students, who coordinated nationwide protests yesterday against the Coalition's plans to deregulate tertiary education.

The Sydney University's Liberal Club released a statement on Facebook, saying Thursday's debating event was "subject to a violent riot by a fringe group of students on the extreme left".

"I'm sure all Australian students stand with me in condemning this unprovoked and violent riot," the statement quoted the club's president, Alex Dore, as saying.

"This riot was organised by the usual suspects from Sydney University's extremist rent-a-crowd, who have nothing better to do than to disrupt civil debate with their militant tactics."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 4 seconds 3 m 4 s Uni students ramp up protests ( Jason Om )

On Wednesday Prime Minister Tony Abbott and Mr Pyne cancelled a visit to Deakin University in Geelong after security advice from the Australian Federal Police.

The federal budget included plans to deregulate university fees from 2016, allowing universities to charge what they like for courses.

The interest rate on student loans will also increase and the income threshold for when students need to start paying the money back will be lowered.

Mr Pyne made it clear earlier on Thursday that despite protests from students there will be no changes to the education reforms.

"I don't swallow the argument that students are somehow being mistreated or burdened," he said.

"That doesn't change the government's mind. We have to do this for the county, and we have to do it for the students."

He rejected calls from Universities Australia for a delay to the start of deregulated fees in 2016 so universities could have more time to set fees.

"Delaying it is simply the easy way out because Universities Australia can't agree amongst themselves," he said.