Avril Lavigne is fighting back against claims she's a songwriting plagiarist.

She takes particular aim at fellow Canadian songstress Chantal Kreviazuk's suggestion that the punk princess swiped one of her tunes for her new album, The Best Damn Thing.

Avril Lavigne, seen here in Los Angeles in November, has lashed back against those who question her songwriting abilities in a message on her website.
(Branimir Kvartuc/Associated Press)

"Chantal's comments are damaging to my reputation and a clear defamation of my character and I am considering taking legal action," Lavigne wrote on her website late Friday.

Kreviazuk's recent claims to Performing Songwriter magazine are nothing more than sour grapes, Lavigne says, resulting from unsuccessful songwriting collaborations between the two.

"My decision to discontinue working with Chantal after co-writing together on my second record was simply based on the fact that we had no hits together. That is why her name is not on this record, despite her numerous attempts to be included, which were always denied. From my perspective, this is a clear case of bitterness."

Lavigne also alleges that Kreviazuk e-mailed her after the magazine hit the stands to apologize for her suggestion that the song Contagious on Lavigne's latest hit album was hers.

"I forgive her but I have to put the truth out there so my fans are not confused by these false accusations," Lavigne wrote.

Lavigne, repeatedly dogged by accusations she doesn't write her own songs, was equally miffed about being dragged into a legal battle to prove she wrote her chart-topping hit, Girlfriend.

A pair of U.S. songwriters allege her catchy single sounds suspiciously like a song called I Wanna Be Your Boyfriend, released by the Rubinoos in 1979.

The American song features the upbeat chorus: "Hey, hey, you, you, I wanna be your boyfriend," much like Lavigne's boppy refrain, which declares: "Hey, hey, you, you, I don't like your girlfriend."

"I had never heard this song in my life and their claim is based on five words," Lavigne wrote. "All songs share similar lyrics and emotions. As humans we speak one language. … Simply put, I have been falsely accused of ripping their song off."

Earlier this week, Lavigne's manager, Terry McBride, scoffed at the charges, calling the suit "baseless" and little more than a "case of legal blackmail.

"Avril's a great songwriter and she's proving it over and over and over again," McBride said from Vancouver, where he runs Nettwerk Music Group. "Avril's very, very sensible. She knows music well. If the chords had been similar, the melodies had been similar, lyrics had been similar … she would have gone, `OK, I can see their point.' But nothing's similar."

Lavigne, who grew up in Napanee, Ont., has also had to deflect accusations from the Matrix, the production team behind hits Sk8er Boi and I'm With You.

Songwriter Lauren Christie told Rolling Stone that Lavigne did little but "change a word here or there," but Lavigne has insisted they crafted the melodies and lyrics together.

"Let it be crystal clear that I have not ripped anyone off or done anything wrong," Lavigne wrote on her website Friday. "I do not deserve this negative press and attention. I take pride in the songs that I write and appreciate the opportunities to work with some great writers and musicians."