Britain on Friday condemned the U.S. over its refusal to extradite an American diplomat's wife charged with causing the death of a British teenager in a road accident last August, saying Washington's decision amounted to a "denial of justice."

"We are disappointed in this decision, which appears to be a denial of justice," a spokeswoman for the Britain's Home Office said. "We are urgently considering our options."

Earlier on Thursday, U.S. Secretary of State Mike Pompeo turned down London's extradition request for Anne Sacoolas, 42, who had claimed diplomatic immunity and returned to the U.S. after the fatal accident outside RAF Croughton – a British air force base used by the U.S. as a communications hub – in Northamptonshire, England, on August 27.

Sacoolas, identified as the wife of U.S. intelligence official Jonathan Sacoolas, was driving on the wrong side of the road when her car crashed head-on into the motorbike of 19-year-old Harry Dunn, leaving the teenager dead.

In December, Sacoolas, who admitted to being the driver, was charged by British police with causing death by dangerous driving. However, she has cited diplomatic immunity while refusing to return to Britain to face justice, as Dunn's parents have demanded.

The U.S. State Department confirmed rejecting Britain's extradition request, saying Sacoolas had "immunity from criminal jurisdiction" at the time of the crash, and for the duration of her stay in the UK.

"If the United States were to grant the UK's extradition request, it would render the invocation of diplomatic immunity a practical nullity and would set an extraordinarily troubling precedent," it said in the statement.

While immunity normally applies on diplomats and their dependents based in London, a special arrangement has been in place since 1994 for U.S. diplomats working at RAF Croughton, according to British media reports.

The case has put pressure on the "special relations" between the U.S. and Britain and triggered public debates over the scope and validity of diplomatic immunity in matters not linked to national security.

Dunn's parents, Charlotte Charles and Tim Dunn, said they "were not at all surprised" by Pompeo's decision, adding that they would continue to fight for justice for their son.

"This is a lawless, corrupt administration that appears intent on attacking even its closest international ally," family spokesman Radd Seiger said. "If Trump and Pompeo think this is an end to the matter, they have another thing coming to them," he added, saying the family would meet with the government to discuss their next steps.

In October, Dunn's parents visited the White House and met U.S. President Donald Trump, who they described as "warm and welcoming." At the same time, they also criticized White House's underhand attempts to force a meeting with Sacoolas.

Describing the crash as a "terrible accident," Trump, however, tried to lighten the matter saying it was common for Americans in Britain to make the blunder of driving on the left side of the road.

(With input from agencies)