WASHINGTON, June 14 (Reuters) - U.S. President Donald Trump will host seven mixed martial arts fights on Sunday in a specially built arena on the South Lawn of the White House to mark his 80th birthday, in an event that highlights his unorthodox style at a tense moment in his presidency.

Seventeen months into his second term, Trump has repeatedly broken with presidential protocol to attract attention and project power. His latest stunt is the UFC's Octagon, an eight-sided mixed martial arts cage erected within sight of his White House bedroom for the event, titled UFC Freedom 250. The title refers to the bicentennial of the United States next month.

This event comes at a time when Trump is facing a four-month-long war with Iran that has pushed consumer prices to their highest level in three years and public opinion polls show are worrying many voters. It also coincides with his birthday and his efforts to counter perceptions that he has become an ineffective president.

Trump is set to watch 14 mixed martial arts fighters from five countries kick, punch, and wrestle for victory before an expected crowd of 4,000 inside a 28-meter-high temporary arena called "The Clow." The main event, scheduled to last five rounds, features lightweight champion Ilija Toporia against former interim champion Justin Gaethje. The fights are scheduled to begin at 8 p.m. (00:00 GMT Monday).

Tickets were not made available to the public. A source familiar with the matter stated that some tickets were given to guests who paid more than $1 million. The Trump administration indicated that a quarter of the attendees would be military personnel.