A leading humanist group in the UK has called for the release of the man who heads the Humanist Association of Nigeria.

Mubarak Bala was detained on account of his activism in Kaduna, Humanists UK says.

"The arrest comes following a pattern of online and physical harassment, culminating in a legal petition to the police accusing him of being 'provocative and annoying to Muslims' on Facebook'," the group said in a statement.

Humanists UK, alongside Humanists International, says it fears that he may be handed over to the authorities in neighbouring Kano state, where, if charged with blasphemy, he could face the death penalty under the state’s Islamic laws.

Humanists UK says it has written to the UK Foreign Office and the relevant UN special rapporteurs to raise Mr Bala’s case and apply pressure on the Nigerian authorities to request his safe release.

The group is also hiring legal representation in Lagos.

Nigeria is a deeply religious country. The state of Kaduna mirrors the country as a whole, with the south largely inhabited by Christian groups, while Muslims form a majority in the north.

In 2014 the BBC reported that Mr Bala was being treated at a mental institution in Kano state because he said he did not believe in God