Provincial authorities in south-western Afghanistan have thrown thousands of books, mainly about Shias or Shia Islam, into a river.

The Nimroz government said the books, copies of 11 titles, undermined national integrity and could fuel ethnic problems.

Officials said they were acting on instructions from the ministries of culture and justice.

But ministerial spokesmen have denied this in interviews with the BBC.

The books, which circulate freely elsewhere in Afghanistan, were seized six months ago as they were being imported from Iran.

A BBC correspondent says the destruction of the books in this way is thought to be unprecedented.