Reports from Nigeria say a terracotta head worth three million dollars has disappeared while being transported from Geneva to Lagos.

The ancient artefact was stolen six years ago from a museum at Ile Ife in the south-west, but Nigerian museum officials tracked it down to Switzerland last year.

It was due to be returned early this month via Luxembourg.

Officials at the National Museum in Lagos quoted in the Guardian newspaper said the air freight company had now told them the terracotta head vanished in transit.

Correspondents say theft of ancient artworks is increasingly common in Nigeria, with many being sold to Europe and the United States.

From the newsroom of the BBC World Service