HIV-positive couples are being paired up for marriage by a northern Nigerian state in an attempt to reduce the spread of the disease

But international AIDS experts have voiced concern at the plan. Warren Naamara from UNAIDS said the two people could have different strains of the virus, which could interact. He said the couples should use condoms. Around 70 couples have been matched up in the last few weeks, according to Bauchi state authorities. Authorities in the state say they are trying to stop HIV spreading and battle the "isolation and stigma" of the disease. Some 3% of Nigeria's adult population - 2.4 million people - is estimated to be HIV-positive. Bauchi State operates under Sharia, or Islamic laws, and the use of condoms is not encouraged.