LONDON: Former US Secretary of State Mike Pompeo has accused Britain of paying “blood money” to Iran to secure the release of two British-Iranian nationals held hostage by the Tehran regime.

Pompeo, who has long taken a hard stance against Iran, claimed the £400 million ($530 million) paid to Tehran will be used to “terrorize” opponents.

Downing Street has said that it had put in place “rigorous safeguards” to ensure the money would not be used for weapons, but rather for “humanitarian” purposes.

Nazanin Zaghari-Ratcliffe and Anoosh Ashori were released late on Wednesday after years of detention in Iran. Reports claim that the aircraft carrying them to freedom was not allowed to take off until the British cash had been transferred.

Pompeo tweeted on Wednesday: “The UK priced taking & holding its citizens hostage at $530 million. We prevented paying blood money — not rewarding hostage-takers.”

He added: “That cash will terrorize Israel, UK & US. Appeasement feels good until it fails — it always does.”

Iran has long maintained that the money was owed for an undelivered order of thousands of tanks and other vehicles agreed between the UK and Iran’s pre-revolutionary government.

While conceding the debt was legitimate, Britain has taken pains to insist that the release of the hostages was not related to the money.

During his tenure as the top US diplomat, Pompeo oversaw the collapse of the 2015 KJCPOA (Joint Comprehensive Plan of Action) — the “Iran deal” — which led to the re-imposition of sanctions on Iran, as well as heightened Iranian nuclear research activity.

Pompeo’s tough stance on Iran has led State Department officials to conclude that he could be at risk, and the Associated Press revealed on Saturday that the department spends about $2 million per month on security for him.

The former envoy and another former top aide face “serious and credible” threats from Iran, the department said.