The BBC has again accused Iran of escalating a campaign of intimidation against its Persian journalists and increasingly targeting the relatives of staff inside the country.

The British broadcaster said on Monday that its BBC Persian journalists were witnessing “a disturbing rise in the persecution of their family members”.

People had endured random interrogations, travel bans, passport confiscations and asset seizure threats, it said.

Staff – both in the UK and elsewhere – had not been able to return to Iran, and had also been directly targeted with violence and threats aimed at pressuring them to abandon their work, the BBC said.

“We call on the Iranian authorities to immediately cease this campaign of intimidation,” the BBC’s director general Tim Davie said in a statement on Monday.

Tehran is yet to respond to the latest allegations from the BBC. The Iranian regime has previously been accused of conducting unlawful operations against journalists abroad.

It has denied those allegations and accused the BBC of spreading false information to encourage its overthrow.

BBC News Persian reaches a weekly global audience of almost 22 million people, including around 13 million in Iran, where the service is banned.

The BBC has previously said that the Iranian regime has targeted its Persian language journalists covering the country over the past decade – prompting the broadcaster to lodge urgent complaints with the UN Human Rights Council in 2018 and again in 2022.

But there had been a “significant and increasingly alarming escalation” recently, the BBC said on Monday.

“In addition to enduring personal security threats from Iranian state actors operating beyond Iran’s borders, BBC News Persian journalists are now witnessing a disturbing rise in the persecution of their family members inside Iran,” said Mr Davie.

“This persecution is a direct assault on press freedom and human rights. It must end now.”

The broadcaster said it was preparing a fresh complaint to the UN.

The UN’s secretary general and its special rapporteurs have previously raised concerns about Iran’s treatment of BBC staff and warned that harassment, surveillance and death threats violated international human rights law.