Belgium was told by the European Union to remedy gaps in its border security just weeks before suicide bombers attacked Brussels killing 31 people and wounding about 300, according to a report published Thursday. The revelation that a list of recommendations was sent to Brussels in late February urging it to repair its "deficient" security checks came amid Belgian and French media reports that a second attacker, possibly at large, is suspected of taking part in Tuesday's metro bombing alongside Khalid El Bakraoui. El Bakraoui's brother Ibrahim, and Najim Laachraoui, were identified as two suicide bombers who targeted Brussels Airport the same day. A third unidentified airport suspect is still being sought by police. The disclosure that the EU expressed its concerns to Belgium about serious security holes in its border controls was published by British newspaper the Daily Telegraph.