United Nations experts have demanded the immediate release of an Eritrean journalist who has been held without trial for 20 years.

A UN special rapporteur on human rights said Dawit Isaak had never been charged and had never spoken to his lawyer.

She said there were fears for his life and urged the Eritrean authorities to present evidence that he was alive.

Mr Dawit, who is a Swedish-Eritrean national, set up one of the country's first independent newspapers in the 1990s.

He was arrested after it published an open letter from politicians demanding political reform.