The Swiss authorities say that at least three people have been killed and another seventeen injured in an explosion near the centre of the capital, Bern.

Police said the powerful blast destroyed a five-storey block of flats, causing it to collapse like a pack of cards.

A police spokesman said the cause was not known but there was no evidence to suggest it was a bomb.

Fire fighters and rescue-workers are searching the rubble for a number of people reported to be still missing.