A former Shiv Sena leader today slammed Sena chief Balasahib Thackeray for his latest outburst against Biharis and charged him with undoing the unification efforts of Sardar Vallabh Bhai Patel. Former vice-president of Shiv Sena, Delhi, Abhimanyu Gulati said if Bal Thackeray refuses to end his anti-north Indian triade, then ''like minded'' people may join hands under a new banner to retaliate. ''Sardar Patel took efforts to convert princely states into a united India. But now these leaders were trying to undo his efforts,'' he alleged. Shiv Sena Chief Bal Thackeray's remarks against Biharis were published today in the editorial of party's mouthpiece ''Saamna''. A report from Mumbai said the police was taking legal opinion on the issue, after which appropriate steps would be taken.