LONDON (Reuters) - British Prime Minister Boris Johnson said on Monday that he wanted a U.S. diplomat’s wife who was involved in a fatal car crash to return to Britain and that it was wrong for her to have used diplomatic immunity to leave the country.

“I hope that Anne Sacoolas will come back and will engage properly with the processes of law as they are carried out in this country,” Johnson said in a television interview, adding the issue was being raised with the U.S. ambassador in London.

“If we can’t resolve it, then of course I will be raising it myself personally with the White House.”

Harry Dunn, 19, died in August after a road collision near RAF Croughton, an air force base in Northamptonshire in central England that is used by the United States.

A spokesman for the U.S. Embassy in London said: “Any questions regarding a waiver of the immunity with regard to our diplomats and their family members overseas in a case like this receive intense attention at senior levels and are considered carefully given the global impact such decisions carry.

“Immunity is rarely waived. The U.S. Embassy has been and will continue to be in close contact with appropriate British officials.”

Northamptonshire police’s chief constable, Nick Adderley, told BBC television that investigators knew that a vehicle which left the RAF base was on the wrong side of the road at the time of the accident.

Dunn’s mother told the broadcaster she wanted the diplomat’s wife to return to face justice.

“If she’d have stayed and faced us as a family we could have found that forgiveness ... but forgiving her for leaving, I’m nowhere near,” Charlotte Charles said.

The U.S. Embassy spokesman said: “We express our deepest sympathies and offer condolences to the family of the deceased in this tragic traffic accident.”

He declined to comment on the identity of the driver.