CAIRO (Reuters) - A foreign fighter captured during a raid on Islamist militants blamed by Egypt for a deadly attack in its western desert last month is a Libyan national, the Egyptian interior ministry said on Thursday.  The captured fighter, Abdelrahim Mohamed al-Mesmari, 25, is from the eastern Libyan town of Derna, an interior ministry statement said.  A little-known group called Ansar al-Islam claimed responsibility for the Oct. 21 attack. Three security sources said at the time that at least 52 police officers and conscripts were killed but the interior ministry refuted that figure the next day and said only 16 policemen had been killed. The new militant group risks opening up another front for security forces far beyond the remote northern Sinai, where they have battled an Islamic State insurgency since 2014. The Egyptian air force killed the 15 militants responsible for the deadly attack and later arrested 29 others for adopting the same ideology, the statement said.  The militants were being trained in Derna, it added.  
Egypt says captured fighter involved in deadly desert attack is Libyan