Actor John Cusack has hit out at sports fans in a foul-mouthed rant after he was pictured sitting at the start of a military salute during a Chicago Cubs baseball game last night.

The Con Air star, who is from Chicago, Illinois, was in a seat behind the home plate at the Cubs-Phillies game at Wrigley Field when spectators were invited to stand for a fourth inning 'Boeing military salute'.

As Cusack remained sitting while others took to their feet, one fan captured the moment before posting it online.

In a scathing Twitter response, Cusack repeatedly denied that he remained seated, blasting 'maga f***s' loyal to Trump of vastly exaggerating the incident because he didn't stand up 'fast enough'.

Cusack is well know for his left-wing politics and has criticizes President Trump almost daily. The Bernie Sanders supporter even visited Julian Assange while he was holed up in the Ecuadorian embassy in London.

Take a stand: John Cusack was pictured sitting during what is claimed to be the start of a 'military salute' organised by aircraft and weapons manufacturer Boeing during a Chicago Cubs match yesterday evening

'I didn't stand up for Boeing military salute - fast enough for some maga f*** - see? don't even have taste not to brand weapons company all over score board,' Cusack said in a scathing Twitter rant

Others reacted angrily to the post on Twitter, labeling Cusack as 'disrespectful' and 'ungrateful'.

One commentor wrote: 'Shameful. Those who have served defending our rights deserve the ultimate respect and the least we can do is give them a standing ovation.'

Cusack later saw the picture being posted online and defended himself, claiming that he did eventually stand up just 'not on cue'.

'I stood up- just not on que - like an Obedient pet I made a film called war inc - watch that,' read a post by the actor.

Small news outlet CWBChicago posted the photo, saying: 'Here's John Cusack, staying firmly seated during tonight's military salute at Wrigley Field'

The Cubs play a set of home games against the Philadelphia Phillies. On the night that Cusack was pictured during the fourth inning salute, the Cubs won 8-4

He then received backlash to his tweet, mostly from Trump supporters, who claimed that he didn't care about veterans.

A Trump-supporting account said: 'Bro...show some class. I always liked you in movies.'

Another read: 'Has-been..... trying to be relevant aren't you? Look at me disrespecting America's Military. Sad evil hypocrite loser.'

But the Being John Malkovich star then ranted that the salute, which was paid for by Boeing, was tainted with advertisements for weapons manufacturers which 'Make America Great Again' supporters had overlooked.

Cusack ranted in replies to several tweets over his picture of him seen seated while thousands of spectators got to their feet for a military salute

'I didn't stand up for Boeing military salute - fast enough for some maga f*** - see? don't even have taste not to brand weapons company all over score board.'

'Trump. Wraps himself in the us flag - literarily hugs it . You think he's a patriot? (sic)' he then asked rhetorically.

Boeing, which produces weapons technology for the American military, signed a $3 million deal with the Chicago Cubs to hold a series of military salutes and first pitches throughout the year.

According to American media outlet SBNation, the US Department of Defense paid over $10 million in marketing deals to sports stadium to hold military salutes and parades other than the National Anthem.