British foreign minister James Cleverly said on Saturday Britain would temporarily withdraw its ambassador from Iran following the execution of British-Iranian national Alireza Akbari and was considering what further action to take against Tehran.
"It is important to recognize that our response are not necessarily limited to the actions that I've announced today," he told broadcasters.
"I will decide obviously in consultation with my colleagues in government what further actions we may choose to take but I'm not going to speculate about those today."
Earlier the same day, Cleverly sanctioned the Iranian chief prosecutor, drawing immediate response from Iran officials.
"Sanctioning him today underlines our disgust at Alireza Akbari's execution," Cleverly said on Twitter. "The prosecutor general is at the heart of Iran's use of the death penalty. We're holding the regime to account for its appalling human rights violations."
Minutes later, Iranian officials summoned the British ambassador to the Islamic Republic over "meddling."
The Iranian foreign ministry announced on Saturday it had summoned the ambassador over what it called London's "meddling in Iran's national security realm." Earlier on Saturday, Britain had described the execution by Iran of British-Iranian national Alireza Akbari as barbaric and said it would not go unpunished.
French Foreign Minister Catherine Colonna summoned Iran's charge d'affaires over the execution.
He was "warned that Iran's repeated violations of international law cannot go unanswered, particularly with regard to the treatment of foreign nationals whom it arbitrarily detains," a foreign ministry statement said.
French President Emmanuel Macron added on Saturday that the execution of Akbari is a heinous and barbaric act, saying he stands in solidarity with Britain.
The US ambassador to London said on Saturday the United States condemned the execution of British-Iranian national Alireza Akbari, describing it as "appalling."
"The execution of British-Iranian citizen Alireza Akbari in Iran is appalling and sickening," Ambassador Jane Hartley said on Twitter. "The United States joins with the UK in condemning this barbaric act. My thoughts are with Alireza’s family."
Iranian tensions with the West
Iran's ties with the West have also been strained by its support for Russia in Ukraine, where Western states say Moscow has used Iranian drones during the invasion.
Britain, which has a long history of fraught ties with Iran, and other Western states have been fiercely critical of Tehran's crackdown on anti-government protests, sparked by the death in custody of a young Iranian-Kurdish woman in September.
Iran has issued dozens of death sentences as part of the crackdown, executing at least four people.