Iranian President Hassan Rouhani defended Saturday's execution of a prominent dissident journalist based in France and captured by Iran last year, saying the death sentence passed on Ruhollah Zam was carried out lawfully.

European countries “have the right to comment, but Zam was executed upon a court's ruling,” Rouhani told a televised news conference, noting that the judiciary was independent.

“I think it's unlikely that this will hurt Iran-Europe relations.”

Zam had been based in Paris and was captured last year in circumstances that have not been officially disclosed. A news agency close to Iran's Revolutionary Guards said last week he had been captured while in Iraq.

He was convicted of fomenting violence during anti-government protests in 2017. His Amadnews social media feed had more than 1 million followers.

France called Zam's execution on Saturday barbaric and unacceptable.

Iran's foreign ministry summoned envoys from France and from Germany, current holder of the European Union's rotating presidency, to protest over criticism of the execution, Iranian media reported on Sunday.

Meanwhile, the UN rights chief voiced outrage on Monday at Iran's execution of Zam, and urged Tehran to halt its “alarming and increasing” use of the death penalty.

“I am appalled at the execution in Iran on December 12 of Ruhollah Zam,” Michelle Bachelet said in a statement.

“His death sentence and execution by hanging are emblematic of a pattern of forced confessions extracted under torture and broadcast on state media being used as a basis to convict people. “