US presidential candidate and real estate mogul Donald Trump filed a $500m lawsuit on Tuesday against Univision over the Spanish-language TV network’s decision to end its contract to broadcast the Miss USA pageant, which is co-owned by Trump.

Univision said last week it would not air the 12 July pageant because of what it called insulting remarks about Mexican immigrants made by Trump when he announced he was running for the 2016 Republican presidential nomination.

The 19-page lawsuit accuses Univision of a “thinly veiled attempt” to stifle Trump’s freedom of speech in order to boost Democratic frontrunner Hillary Clinton. The network’s principal owner, Haim Saban, is a Clinton fundraiser, according to the lawsuit.

While officially announcing his candidacy on 16 June, Trump accused Mexico of sending rapists and other criminals to the US.

“They’re bringing drugs, they’re bringing crime, they’re rapists, and some I assume are good people, but I speak to border guards and they tell us what we are getting,” he said at the time.

In a statement on Tuesday announcing the lawsuit, which he had vowed to file, Trump refused to back down from his comments.

“Nothing that I stated was different from what I have been saying for many years,” he said. “There is a high level of crime occurring in this country due to unchecked illegal immigration.”

Nevertheless, he added that he has “great respect for Mexico and love for the Mexican people and their tremendous spirit”.

In a statement, Univision representative called the lawsuit “both factually false and legally ridiculous”.

Last week, the network said it would not air the pageant and would sever ties with the Miss Universe organization, which had been a joint venture between Trump and Comcast-owned NBCUniversal, in light of his “recent, insulting remarks about Mexican immigrants”.

NBC also cut ties with the Miss USA and Miss Universe pageants on Monday, citing Trump’s comments. Trump previously said he would not take part in his NBC reality television show, The Apprentice, while he sought the White House.

Trump is considered a long shot to get the Republican nomination despite his name recognition.