Former US president George H. W. Bush has apologised after an actress nearly 60 years his junior accused him of groping her from his wheelchair.

Heather Lind, 34, claimed Mr Bush, 93, assaulted her four years ago while they posed for a photograph alongside the president's wife Barbara Bush.

In a post on social media Ms Lind claimed: "He didn't shake my hand. He touched me from behind from his wheelchair with his wife Barbara Bush by his side. He told me a dirty joke.

"And then, all the while being photographed, touched me again. Barbara rolled her eyes as if to say 'not again'. His security guard told me I shouldn't have stood next to him for the photo."

In a statement Mr Bush's spokesman Jim McGrath did not deny the allegation but described the incident as an ill-judged attempt at humour.

The spokesman said: "President Bush would never, under any circumstance, intentionally cause anyone distress, and he most sincerely apologises if his attempt at humour offended Ms Lind."

Ms Lind was starring in "Turn: Washington's Spies," a 2014 Revolutionary War drama and met Mr Bush along with fellow cast members at a screening in in Houston, Texas.