The BBC is appealing to the United Nations in Geneva to protect the human rights of its journalists and their families as Iranian authorities escalate "years of persecution and harassment".

The unprecedented move follows its own unheeded calls to Tehran to end the harassment of staff working for the British broadcaster's Persian Service, according to BBC director general,Tony Hall.

"The BBC is taking the unprecedented step of appealing to the United Nations because our own attempts to persuade the Iranian authorities to end their harassment have been completely ignored," Hall said in a statement.

"In fact, during the past nine years, the collective punishment of BBC Persian Service journalists and their families has worsened."

Lawyers for the BBC World Service in October filed an urgent appeal to UN Special Rapporteurs David Kaye and Asma Jahangir on behalf of its Persian Service staff.