Britain on Saturday urged the United States to reconsider its decision to allow a diplomat's wife, who's suspected of involvement in a fatal traffic crash, to use her diplomatic immunity to leave Britain.

The wife of the U.S. diplomat has left the United Kingdom after reportedly becoming a suspect in the fatal crash that killed a British teenager in August.

British Foreign Secretary Dominic Raab. [File photo: VCG]

Harry Dunn, 19, of Charlton, Banbury, was killed when his motorbike crashed with a car near RAF Croughton on Aug. 27 in Northamptonshire in the East Midlands of England. RAF Croughton is used by the U.S. military as a communications hub.

Police told Sky News that their initial findings show that Dunn was riding his motorbike on the correct side of the road, but that the woman, who pulled out of the airbase onto the wrong side of the carriageway, hit him head-on. He suffered multiple injuries and died later in hospital.

British media reports did not give information on the American suspect's identity, but just describe her as "wife of a U.S. diplomat."

Also on Saturday, British Foreign Secretary Dominic Raab said in a statement that he had expressed his "disappointment" to the U.S. ambassador about her departure.

Local police said that they applied for a waiver from diplomatic immunity so they can conduct investigations and an interview.

The U.S. Embassy in London said: "Embassy officials are in close contact with the appropriate British officials on this matter."

"Due to security and privacy considerations, we cannot confirm the identity of the individuals involved, but we can confirm the family has left the UK," it added.