Donald Trump turns down 'open invitation' to attend one of America's biggest sporting events after snubbing close friend

Donald Trump has turned down an 'open invitation' to attend a major sporting event this weekend, it has been reported.

The US President has attended several sporting occasions since the beginning of his second stint at the White House, including the NFL Super Bowl and NASCAR's Daytona 500.

On Sunday, the 109th running of the Indianapolis 500 will take place at the Indianapolis Motor Speedway, with Trump receiving an 'open invitation' from track and IndyCar series owner Roger Penske to personally attend.

Penske is a longtime friend of the President, but Politico report that Trump has declined the invitation to attend.

Team Penske, who field three cars in the iconic IndyCar race, visited the White House last month.

The topic of conversation quickly moved on to the Indy 500, with Trump commenting: "I might have to get there this year."

However, it is reported that the US President will not be in Indiana on Sunday and instead has other matters to attend to.

The race was won by Team Penske's Josef Newgarden last year, though the cars belonging to himself and team-mate Will Power have been under significant scrutiny in the lead-up to the big occasion.

Both cars were withdrawn from qualifying by IndyCar officials after it was found that they had an illegally-modified attenuator - a part on the rear of the car which effectively helps to absorb G-forces in the event of a major crash.

It was reported that Penske modified the size and appearance of the attenuator, which is banned under IndyCar regulations, and had been using the illegal part for at least a year without being noticed.

Indy chiefs responded by sending Newgarden and Power to the back of the grid, meaning they will start Sunday's Indy 500 from 32nd and 33rd place.

IndyCar's official statement on the entries of Josef Newgarden and Will Power (Image: Twitter/@IndyCar)

Elsewhere, there are a number of ex-Formula 1 drivers in the field, with Takuma Sato (twice) and Marcus Ericsson (once) among the previous winners of the iconic race.

Sato, 48, is in second place on the grid behind former F2 driver and IndyCar rookie Robert Shwartzman.

F1 hopeful Pato O'Ward is looking to win his first Indy 500 with Arrow McLaren after finishing second behind Newgarden last year, while NASCAR's Kyle Larson returns to attempt an unprecedented double of winning the Indy 500 and NASCAR's Coca-Cola 600 in Charlotte - 582 miles away - on the same day.