The United Nations says it's withdrawing non-essential staff from the eastern Afghan city of Jalalabad after widespread rioting that's left at least four people dead and scores of others injured.

Police opened fire after a crowd of several thousand set fire to the governor's house, the Pakistani consulate and several aid agency buildings.

Shops and cars were also attacked.

The violence was sparked by the alleged desecration of the Koran by US military interrogators at Guantanamo Bay.

The US Embassy in Kabul says it's "deeply concerned" at the violence, and says the American government will investigate the desecration allegations.