Sinn Féin's Mary Lou McDonald is to raise concerns with the US ambassador after she was subjected to "invasive searches" on a flight home from the United States.

Ms McDonald and party leader Gerry Adams said the searches were completely unnecessary.

The deputy leader said: “It is quite something that we are subjected to the level of security checks entering but also leaving the United States.

“I just want to say it is the right of any jurisdiction or any state to have rigorous security measures in place, that is not an issue.

“We are not looking for special treatment but I would ask for myself as to why I would merit special security checks, why any member of Sinn Féin merit special security checks.”

Ms McDonald said there was no excuse for why she or her colleagues are being treated the way they are being treated.

She said the security checks were “heavy-handed and invasive” that were completely unnecessary and “off the wall”.

The deputy leader is to seek a meeting with the US ambassador to Ireland Kevin O'Malley, requiring an explanation.

Mr Adams also confirmed he is to write to the White House this week to seek further explanation as to why he was refused entry to a reception there.

The Sinn Féin president said it was not acceptable for a guest to be invited to an event and then denied access.

He said: “That is not acceptable and I do accept the apology that was given but do not accept the explanation.”

Mr Adams was invited to the White House for the annual reception hosted by US president Barack Obama last week.

However on arrival he was declined entry after being subjected to searches for up to an hour.

The Secret Service has apologised to Mr Adams for the incident.