Newcastle United have stepped up their interest for Fenerbahce striker Moussa Sow, [football] direct news understands.The 28-year-old striker has scored an impressive nine goals in 18 games for the Turkish side this season, gaining him interest from the likes of Arsenal and Tottenham in January.googletag.cmd.push(function() { googletag.display(“div-gpt-ad-1389116196215-0”); });However, those two clubs have now been joined in what could be a summer transfer battle by Newcastle United and Russian side Rubin Kazan.Newcastle are keen to add more firepower to their attack after some poor performances by Papiss Cisse, who now looks likely to leave the club in the summer.Sow is under contract until June 2016 and the Turkish club have slapped a transfer value of 12m on the striker.