Justin Bieber has hit back at claims he was a "brat" on the set of ‘CSI: Crime Scene Investigation'.

The 17-year-old superstar -- who made a guest appearance in the drama TV series playing troubled teen Jason McCann, who was shot dead, in the series finale -- insisted he would continue to be kind" about show cast and crew, but felt it "lame" that actress Marg Helgenberger had spoken out to criticise his conduct.

He tweeted: "It's kinda lame when someone you met briefly and never worked with comments on you. I will continue to wish them luck and be kind.

"I know who I am and sometimes people r just going 2 say what they want. Keep ur head up and be the man ur mama raised.

"Rumors are just that...rumors. In the end if you just be kind and be yourself people will know who you are. That goes for anyone I think." (sic)"

Marg -- who plays CSI investigator Catherine Willows in the show -- had claimed in an interview that the teenage singer had locked a producer in a cupboard and ruined a cake during his brief stint on the programme.

She said: "I shouldn't be saying this but he was kind of a brat.

"He was very nice to me. But he locked one of the producers in a closet and he put his fist through a cake that was on the cast's table."

Despite Justin's conduct on set, Marg, 52, insists he is a competent actor -- especially for someone with no prior experience.

She said: "Justin Bieber wasn't bad. He'd never acted before ... He's better than you'd think."