Amanda Bynes attacks Lance Bass: "You're an ugly ex boy band member"

In the wake of Amanda Bynes' recent arrest, displays of erratic public behavior and Twitter rants, longtime friend Lance Bass took to Las Vegas' Mark & Mercedes 94.1 radio show on Wednesday to speak out about his concern for the troubled starlet, which in turn ignited an all-out Twitter war.

"It's one of those situations where obviously there's some mental problems there and she's not able to see that," Bass, 34, said of the 27-year-old actress. "We all are [able to see it]," he told the radio show.

RELATED PICS: Amanda Bynes Twitter Photo Album

He added, "I'm actually really scared for her, and I hope someone is able to get to her to give her the help she needs."

In response, the "What I Like About You" actress lashed out at the former 'N Syncer, tweeting: "I ignored Lance Bass on Twitter and now he is saying I have a mental illness. Sorry you're an ugly ex boy band member w/ no talent or career."

Bass tweeted in response: "Ouch- The Amanda I know would never had said something like this to me- either this is a fake person or she really does have a mental illness. Way too sad. I reached out- all i can do."

The online war of words continued with Bynes biting back: "I haven't spoken to Lance Bass in 11 years. To say I have a mental illness out of nowhere makes me lash out! You're making me crazy!"

Bass reacted: "Now I really don't think this is Amanda- we shot LoveWrecked together 7 years ago and she was just at my bday party 3 years ago. Hmmm 11?"

Bass and Bynes became friends when the former boy band member produced "Love Wrecked" in 2005, a romantic comedy in which Bynes played the lead.

Covering their bases, the Las Vegas radio station also addressed the Twitter war initiated by Bynes.

RELATED: Amanda Bynes To Sue NYPD & Become A Rapper

The "Hairspray" starlet has been a hot topic following her arrest last week in New York City for allegedly smoking marijuana in the lobby of her midtown apartment building and then throwing a bong out the window when police entered. She has since been released from jail.