By Robert-Jan Bartunek BRUSSELS (Reuters) - More than three times as many migrants were tracked entering the European Union by irregular means last month than a year ago, official data showed on Tuesday, many of them landing on Greek islands after fleeing conflict in Syria. While the increase recorded by the European Union's border control agency Frontex may be partly due to better monitoring, it highlighted the scale of a crisis that has led to more than 2,000 deaths this year as desperate migrants take to rickety boats. Italian police said they had arrested eight suspected human traffickers that they said had reportedly forced migrants to stay in the hold of a fishing boat in the Mediterranean as 49 of them suffocated on engine fumes.