A court hearing has been granted to the family of Nnamdi Kanu, to challenge the UK government for not intervening in his case with the Nigerian government.

Kanu, a British citizen who was allegedly taken to Nigeria in an act of extraordinary rendition, is the leader of the Indigenous People of Biafra, a prominent separatist movement proscribed in Nigeria.

He was arrested in Kenya in June last year before being transported against his will to Nigeria, where he has been held ever since.

The UN working group on arbitrary detention in July published an opinion that the father of two had been subject to extraordinary rendition and said he should be released immediately.

However, successive UK foreign secretaries, first Dominic Raab and then Liz Truss, before she became prime minister, have refused to take a view as to whether Kanu was a victim of extraordinary rendition.

The family has been granted a judicial review to challenge that refusal, arguing that its effect has been that no action has been taken to help him, reports The Guardian UK.

“The British government is well known for its stance on human rights. I believe it must be decisive when it comes to its decision-making about very serious violations of the human rights of British citizens abroad, especially when the facts are clear, as they are in my brother’s case, and when the UN has investigated and reached a firm conclusion that my brother was subject to extraordinary rendition. I am very happy that the court has agreed that a hearing is necessary to decide this important issue,” the IPOB leader’s brother, Kingsley Kanu, was quoted to have said.

Shirin Marker, from Bindmans LLP, who is representing Kingsley Kanu, said it was essential for the new foreign secretary, James Cleverly, to reach a firm conclusion on whether her client’s brother had been the victim of extraordinary rendition in order to decide what steps to take to assist him.

“The evidence available to date establishes that he has been subject to extraordinary rendition and torture or inhumane treatment,” she said. “It is unacceptable for the UK government to continue to prevaricate on this issue. We are glad that the court has now granted permission for this case to move to a final hearing.”

Explaining her decision to grant a judicial review hearing, Mrs Justice Ellenbogen said: “Such decisions/inaction are, in principle, reviewable and do not enter forbidden areas, including decisions affecting foreign policy.”