Pop princess Lady Gaga — famed for hits such as Poker Face — left scores of fans stony-faced at her Belfast gig on Saturday night when she brandished an Irish Tricolour on stage.

Up to 10,000 music lovers packed into the Odyssey Arena for the high-tempo Halloween show, one of three she will perform in the city as part of her Monster Ball tour.

The award-winning diva — real name Stefani Germanotta — belted out hits including Just Dance, Poker Face, Paparazzi, Telephone and Bad Romance.

But her decision to whip out the Republic of Ireland’s green, white and orange flag during the show left a bad taste among some revellers who said it was “inappropriate”.

One fan who travelled to the gig with four pals said she felt Gaga had boobed by wielding the tricolour.

“It was about two-thirds of the way through the show when she came out on stage with the Irish Tricolour,” said the 24-year-old, who didn’t want to be named.

“A lot of people were not impressed and there was a bit of unease in the crowd.

“Some people were making comments and others challenging them.

“It didn’t spill over but I certainly think the atmosphere suffered after that as a result.”

Another said: “I just felt it was inappropriate, but maybe she didn’t realise Northern Ireland is separate from the Republic.”

Gaga made no reference to the flag during the segment of the show, revellers said.

Former Lord Mayor of Belfast, UUP councillor Jim Rodgers, condemned the display of any national flags at such events.

He told the Belfast Telegraph last night: “The Odyssey is a very well-run venue and I don’t think the management will be very happy about this. I think at such events it is wrong for flags of any kind to be displayed.

“You tend to find people at such shows from both religions and those with none, and this won’t go down well at all.”

A spokesperson for the Odyssey Arena was unavailable for comment.

Twenty-four-year-old New Yorker Gaga and her entourage are staying at the Hilton Hotel in Belfast, along with 12 burly bodyguards. She endeared herself to local fans on Saturday evening when she posted a picture of herself in a T-shirt with the message ‘I love Belfast’ across it on Twitter.

Along with the pic she ‘tweeted’: “For Halloween... I’m going to be a little monster! I love you all so much! Celebrate yourself!”

Gaga is rumoured to have tied the knot with boyfriend Luc Carl in Greece earlier this month.

At Saturday’s show she appeared to have gained a few pounds in weight, with rumours circulating she was bulking up in the hope of getting pregnant soon.