Senior Breitbart editor Milo Yiannopoulos has had two speaking engagements cancelled over security concerns.

Yiannopoulos, a leading figure of the controversial “alt-right”, an American far-right movement, was due to appear at North Dakota State University and Iowa State University in December, as part of his “Dangerous Faggot Tour”.

But organisers of both events have withdrawn their invitations, citing student safety and the cost of security. Last month Yiannopoulos’s speech at his former high school in the UK was cancelled also due to security concerns.

Before becoming an editor at Breitbart News, Yiannopoulos made his name as a rightwing internet troll and has become associated with the far-right movement that has attracted racists and white nationalists. He was permanently banned from Twitter in July for his role in the online harassment of the actor Leslie Jones and was also involved in the “Gamergate” movement that disparaged women in the video game industry.

Yiannopoulos accused the universities of “censorship” over the cancellations. “Iowa State and North Dakota State have both showed their cowardice – and their contempt for the wishes and rights of their students – by canceling my events on campus without the balls to say what they were really doing,” Yiannopoulos told the Guardian.

He claimed the universities had deliberately increased their security fees so that organizers would have to cancel. Both colleges say the increases are to pay for extra security, which is required because of previous discord at Yiannopoulos’s events.

Jamal Omar, the vice-chair of the North Dakota College Republicans, announced on Facebook that the Yiannopoulos event, planned for 16 December, had been cancelled. “NDSU College Republicans wants to demonstrate safety for all students and feel that this is the most responsible decision regarding the current safety questions at hand,” he said.

Omar told the Guardian he did not agree with many of Yiannopoulos’s beliefs but had invited him as an example of fringe conservative culture.

“We wanted to present an alternative view to what moderate and average people possess to allow people to make a decision from what they view and see how the content impacts them and the people around them,” he said.

A speech by Yiannopoulos at Iowa State University, planned for 9 December, was cancelled by organizer Austen Giles, after the university said he would need to pay additional security costs due to trouble at previous Yiannopoulos speeches.

“Physical altercations, bomb threats and threats of weapons violence at other universities where Yiannopoulos has appeared or was scheduled to appear resulted in the need for the Memorial Union to require additional security for the event,” the university said in a statement.

Giles, a sophomore in public relations at ISU, told the Guardian he was unable to afford the additional $1,994 that the university had requested for him to host the event. He said he hoped to host Yiannopoulos at some point in 2017.

“It’s very disappointing since I had planned this for over three months,” Giles said. “The encouraging thing is, people from all over the community are emailing me and contacting me to send their best wishes and support.”

Giles said he was a Yiannopoulos supporter who had met the Breitbart editor at one of his previous speaking engagements. “He easily exposes the flaws in political correctness and campus culture,” he said.

Yiannopoulos has been posting the text of his speeches to Breitbart – where Donald Trump’s senior adviser Steve Bannon was executive chair until earlier this year.

Some recent talks are titled “10 things Milo hates about Islam”, “Milo On How Feminism Hurts Men And Women” and “Trannies are Gay”.