Dominic Raab has defended the Government's move to seek legal costs from the family of a teenager who was killed in a crash outside an RAF base.
Harry Dunn's parents are suing the Foreign Office (FCO) having alleged that Mr Raab abused or misused his power as Foreign Secretary by granting diplomatic immunity to the woman thought to be driving the car that hit the 19-year-old.
Mr Dunn was killed in a motorbike crash in Northamptonshire on August 27.
Anne Sacoolas is believed to have been driving on the wrong side of the road when she hit Mr Dunn's motorbike outside RAF Croughton.
The suspect, 42-year-old Mrs Sacoolas, who is married to a US intelligence official, was able to leave the country on a private flight under the benefit of diplomatic immunity following the crash.
The foreign office had told Mr Dunn's family that it would challenge their legal action and invited them to drop the case.
Mr Raab told Sky News that even though it "pains" him, his department would seek costs from the family if the case is taken to court.
He said: "The representative of the family is suing the foreign office and they've talked about a litigation strategy in the US as well.
"They're crowdfunding for that purpose and we just cannot responsibly allow ourselves to be sued without taking the normal action in defending ourselves when the position that the representative and the family are pursuing in law is wrong.
"It pains me because I want to give them the solace of justice in this case. But we also need to protect the taxpayers' money and the legal position that we set out, which is the correct one. So it's very difficult, but that's the position that we're in."
The family spokesman Radd Seiger said Charlotte Charles and Tim Dunn, parents of the 19-year-old, are "livid" at the move, and accused Mr Raab of "lying to the nation".
He said: "Harry Dunn's parents are livid at the Foreign Secretary’s comments on Sky News this morning. They are not engaged in some frivolous vexatious litigation frolic of their own against the FCO. Quite the opposite.
"They are British Citizens who have had their entitlement to justice robbed from them by the US Government under the watch of Mr Raab and the FCO. Mr Raab knows perfectly well that Mrs Sacoolas never had diplomatic immunity.
"He has lied to the parents before and he is now lying to the nation. The parents are entitled to answers and the truth.
"If he is so concerned about taxpayers’ money in the litigation then he would come and talk to us to find a resolution rather than risking having the taxpayers themselves having to pay a very expensive legal bill if the FCO lose.
"He also mentioned that he is doing everything he can to clear a path to justice. He told the country in his statement to the House of Commons on Oct 21 that there were no longer any obstacles to justice.
"He can’t have it both ways. The parents are concerned that the US and U.K. governments are conspiring and colluding to pervert the course of justice by interfering in the CPS’ charging decision and they will not stand idly by whilst that is happening."