The family of teenage motorcyclist Harry Dunn have accused the Prime Minister of having "no wish or intention" to meet them to discuss their son's death.
The 19-year-old's parents, Charlotte Charles and Tim Dunn, had been hopeful of a meeting with Boris Johnson after they said they had "repeated assurances" from senior members of his Cabinet.
In recent weeks, Mr Dunn's parents have met the Home Secretary, Witham MP Priti Patel and Foreign Secretary Dominic Raab and have had numerous discussions with their constituency MP Andrea Leadsom.
Ms Leadsom wrote a letter to the Prime Minister requesting a meeting with the family earlier this month.
Mr Dunn was killed when his motorbike crashed into a car outside RAF Croughton in Northamptonshire on August 27 last year.
Anne Sacoolas, 42, the wife of a US intelligence official, claimed diplomatic immunity after the collision and was able to return to her home country, sparking an international controversy.
The US State Department has said the UK's extradition request for Mrs Sacoolas is highly inappropriate and would be an abuse.
Speaking about their hopes of a meeting with the Prime Minister, family spokesman Radd Seiger said: "
Mr Seiger continued: "Johnson, on the other hand, has done his level best to steer clear of Harry's parents and continues to do so.
"I have made numerous attempts to arrange the meeting and said we will meet anytime, anywhere and the meeting need not be a long one. Each offer has either been rebuffed or ignored."
Asked whether Mr Johnson would meet the family, a Downing Street spokesman said: "The legal process is ongoing and the UK has submitted the extradition request. "The Prime Minister will continue to work to get justice for Harry."