Image caption The picture of Chris Henry, Andrew Trimble, Paddy Jackson, Michael Allen and Paddy McAllister was posted to Jackson's Twitter profile

Ulster Rugby have apologised after a photograph showing four of their players with their faces and bodies coloured with black makeup appeared on a social media site.

The photo was posted on the Twitter profile of Irish international Paddy Jackson.

It shows him with two other Irish internationals, Chris Henry and Andrew Trimble.

The photo has now been removed.

The others pictured are current Ulster player Michael Allen and former Ulster player Paddy McAllister.

Paddy Jackson, Chris Henry and Andrew Trimble were members of the Ireland squad that won this year's Six Nations Championship.

Ulster Rugby said they "apologise unreservedly for any offence".

In a statement, the club said the photograph showed the players at an "Olympic-themed fancy dress party held two years ago".

"It was not the intention of the players to cause upset and the photograph has since been removed."

Image caption Paddy Jackson made the photo his profile picture on Twitter recently

In a statement, the Irish Rugby Football Union said it had contacted Ulster Rugby in relation to this matter was "satisfied that they have addressed it appropriately".

It is believed the men were dressed as members of the Ethiopian Olympic team.

It is not known how long the photograph was online.

Paddy Jackson made it his profile picture on Twitter recently.

Chris Henry posted a similar picture to his Twitter feed on 16 May.

Joseph Ricketts, from ACSONI (African and Caribbean Support Organisation Northern Ireland), told Good Morning Ulster that the photo was "deeply offensive".

Image caption A similar photo was posted on Chris Henry's Twitter feed in May

"I am shocked and appalled by this irresponsible behaviour," he said.

"It's worse than bad taste. One of the characters was seen with a chain around the neck, which mimics the most awful period in history for black people.

"It's nasty and people who have seen it are very appalled by it."

He added: "Whether they were trying to justify it as good craic, or something, people are offended by it and as public figures, which they are, they need to be more responsible in the way they behave."