British Prime Minister Boris Johnson urged U.S. President Donald Trump to reconsider a decision to let a U.S. diplomat's wife use diplomatic immunity after her involvement in a fatal car crash, Downing Street said on Wednesday.

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

"The prime minister urged the president to reconsider the U.S. position so the individual involved can return to the U.K., cooperate with police and allow Harry's family to receive justice," a Downing Street spokeswoman said in a readout of a call between the two leaders.

Trump expressed condolences to Dunn's parents and the two leaders agreed to "work together to find a way forward as soon as possible," the spokeswoman added.

Earlier on Wednesday, Dunn's mother, Charlotte Charles, said after meeting with British foreign secretary Dominic Raab that no progress had been made over the last week.

"Part of me is feeling like it was just a publicity stunt on the UK government side to show they are trying to help," she said.

Raab said he shared the frustration of Dunn's parents.