Bynes to Rihanna: Assault because you're 'not pretty enough'

Amanda Bynes, center, wearing sweats and a blonde wig, shields her face as she is escorted after a Manhattan criminal court appearance. Photo/AP

Amanda Bynes has lashed out at Rihanna, saying Chris Brown beat her because she is "not pretty enough".

The 27-year-old actress - who was charged with attempted evidence tampering, reckless endangerment and marijuana possession in court on Friday (US time), and since has accused her arresting officer of sexually harassing her - launched a bitter attack on the 25-year-old Stay singer on Twitter.

The Easy A star wrote: "Chris Brown beat you because you're not pretty enough," before adding: "@Rihanna no one wants to be your lover so you call everyone and their mother that I almost named my new dog Rihanna."

Brown is still on probation for violently attacking Rihanna before the 2009 Grammy Awards.

Rihanna hit back at Bynes: "Ya see what happens when they cancel Intervention?," which only enraged the She's The Man star further.

In tweets that have since been deleted, the actress responded: "@Rihanna unlike ur fugly faced self I don't do drugs! U need the intervention dog! I met ur ugly face in person! U aren't pretty u know it. (sic)"

The New York Police Department's Internal Affairs Bureau is looking into the serious allegations made by actress is a lengthy Twitter rant on Saturday, during which she accused an officer of entering her apartment illegally, slapping her vagina and lying about her throwing a bong out the window in front of him.

Bynes' parents Lynn and Rick Bynes are reportedly worried she is bipolar or schizophrenic but cannot force her to undergo a mental evaluation.

- Bang! Showbiz