LOS ANGELES • The University of California, Berkeley appears headed for a showdown with right-wing commentator Ann Coulter after her planned appearance at the school was cancelled over security concerns.

The decision to shelve her April 27 talk at the famously progressive campus came days after opponents and supporters of United States President Donald Trump clashed in the city.

It also echoed a similar cancellation in February of a planned speech at the university by a right-wing provocateur and former Breitbart editor, Mr Milo Yiannopoulos, following violent protests.

Ms Coulter reacted angrily to the cancellation on Wednesday, saying in a series of tweets that it amounted to censorship and vowing nonetheless to show up at Berkeley as scheduled. "I am! At Berkeley next Thursday," she tweeted.

She added in another post that she had instructed the Republican student group that invited her "to spare no expense in renting my speaking venue - part of my legal damages".

A spokesman for the university said the school's College Republicans were informed late on Tuesday that the event with Ms Coulter had to be scrapped as the safety of the firebrand conservative commentator and the public could not be assured.

University spokesman Dan Mogulof said concern about security during the event mounted last week after posters appeared on the walls of campus buildings threatening disruptions.

He added that "targeted threats" on two websites had also been discovered.

Last weekend, Berkeley was the scene of fights between pro- and anti-Trump demonstrators that led to at least 21 people being arrested.

Mr Mogulof said campus police had learnt that some of the groups that took part in those clashes "planned to target the appearance of Ann Coulter on campus".

He added that the university hoped to be able to reschedule Ms Coulter's appearance some time in September, after identifying an appropriate venue and working out security arrangements.

AGENCE FRANCE-PRESSE