KABUL (Reuters) - Afghan President Hamid Karzai urged the United States on Saturday to prosecute and punish anyone found guilt of desecrating the Koran as anti-U.S. protests flared for a fifth day. Sixteen Afghans have been killed and more than 100 hurt since Wednesday in the worst anti-U.S. protests across Afghanistan since U.S. forces invaded in 2001 to oust the Taliban for harbouring Osama bin Laden and his al Qaeda network. Newsweek magazine said in its May 9 edition investigators probing abuses at the U.S. military prison at Guantanamo Bay found that interrogators "had placed Korans on toilets, and in...