A DUP MP on Tuesday called on US vice president Joe Biden to apologise for casting a "slur" on Protestants by joking to an Irish delegation that no-one wearing orange was welcome in his house on St Patrick's Day.

Northern Irish Protestants traditionally wear orange during their annual summer parades, while green is used as a symbol by mostly Catholic Irish nationalists and is a theme of St Patrick’s Day celebrations around the world.

A smiling Mr Biden, speaking at the front door of his residence to a delegation led by Taoiseach Enda Kenny, quipped that “if you’re wearing orange, you’re not welcome in here” before adding he was only joking.

Protestant leaders in Northern Ireland were not amused.

“Whether they were intended as a joke or not, the comments are a slur on those who would be known as ‘orange’ ie Protestants,” DUP MP William McCrea said in a statement.

“When Northern Ireland is making such an effort to make St Patrick’s Day an inclusive celebration, Joe Biden’s comments were disgraceful and careless,” he added.

Asked about the request for an apology, an official in Mr Biden’s office said the vice president had made clear he was joking.

Five years ago, Mr Biden incorrectly suggested at a St Patrick's Day reception that the mother of then taoiseach Brian Cowen was dead, saying "God rest her soul", before correcting himself to say "God bless her soul".

Reuters