Suspected Islamist extremists have shot dead 44 worshippers in an attack on a mosque in Nigeria\'s restive northeast, a senior government official said on Monday. \"Gunmen believed to be Boko Haram members entered the mosque and opened fire on Muslim worshippers, killing 44,\" the official said on condition of anonymity because he was not authorised to speak publicly of the attack in the remote town of Konduga on Sunday.