British police officers willtravel to the United States to interview the wife of a US diplomat who was given diplomatic immunity after her alleged involvement in a car crash which killed a British teenager.

"The suspect has co-operated fully with the police and withthe authorities," Nick Adderley, the chief constable of Northamptonshire Police, told reporters.

"She has also requested to be interviewed by British police officers, under caution, in the United States."

Harry Dunn, 19, died in August after his motorcycle collided with a car driven by Anne Sacoolas near RAF Croughton, an airforce base in Northamptonshire in central England used by the US military.

The 42-year-old woman being treated as a suspect in relation to the crash left the UK, despite telling officers she did not plan to do so. 

The US embassy confirmed the incident had involved a vehicle driven by the spouse of a US diplomat assigned to UK who had departed the country, adding that diplomatic immunity was "rarely waived".