Bieber continues Twitter row with Rogen

Justin Bieber is "sorry" he didn't "bow down" to Seth Rogen when they met.

The 'Baby' hitmaker hit back at the 'Bad Neighbours' actor - who previously branded him "obnoxious," "ungrateful," and "insincere" - after Seth recalled the first time they met during an interview on 'The Howard Stern Show', where he called the singer a "motherf***er" who acted like he was the one who had requested to meet the teenage star.