Greg Piaetek is suing a Manhattan bar he says refused to serve him because he was wearing a Trump campaign hat

A Trump supporter has launched legal action against a Manhattan bar he claims refused to serve him because he was wearing a Make America Great Again hat.

Greg Piatek was visiting New York from Philadelphia when he stopped in The Happiest Hour on January 28 for a drink.

The 30-year-old accountant claims he was served one round of drinks before staff noticed the slogan on his hat and told him he wasn't welcome if he supported the president.

Mr Piatek said he was shown the door by a manager after being asked whether the hat was 'a joke'.

'Ignoring me because I’m wearing the hat is ridiculous. It’s really sad,' he told The New York Post on Sunday.

Piatek and his friends were visiting the city when they stopped in to the bar for a pre-dinner drink.

He said he was able to order one round without incident but that when they tried to ask for another from a different bartender, he ignored them.

He claimed that when his friend asked to be tended to, the server responded: 'Is the hat a joke?'

Despite his reluctance, the bartender gave them their drinks but the group faced the same treatment when they asked for a third, he said.

Mr Piatek said staff asked him if the Make America Great Again hat (seen above on the president) was a 'joke' before showing him the door

The Happiest Hour in Manhattan's West Village has not responded to Mr Piatek's complaints

That bartender went further in his criticism, allegedly telling them: 'I can’t believe you would support someone so terrible and you must be as terrible a person!' Don’t even try to order from me. I won’t get you a drink.'

According to the accountant, a manager was then told by the bar's owner to ask him to leave after relaying the message that 'anyone who supports Trump or believes what you believe is not welcome here'.

His lawyer said the incident was 'humiliating'.

The Happiest Hour has not responded to the complaint and did not respond to requests on Sunday.