Niger said that Muammar Gaddafi's son Saadi will remain in the West African nation until a United Nations travel ban on him was lifted, despite Tripoli's request for his return, Reuters reported.

Saadi fled south across the Sahara to Niger as his father's 42-year rule crumbled in August. He has been living in Niger since then, and Niamey says he has been granted asylum on humanitarian grounds.

Saif al-Islam, another fugitive son of the former Libyan leader, is believed by many to have sought refuge in Niger or neighboring Mali's desert north but both states say he is not there.

"We are obliged to respect this resolution. He is here, he cannot travel ... Until that resolution is revised, he will stay in Niger," Foreign Minister Bazoum Mohamed told state television.

Interpol has issued a "red notice" requesting member states to arrest Saadi with a view to extradition if they find him on their territory.

Ties between Niger and Libya's interim rulers are strained, with the authorities in Tripoli keen to see the Gaddafi sons, and any assets they took with them, sent home to face trial.