Avril Lavigne is being sued by two songwriters who claim that her hit "Girlfriend" sounds like a track their American power pop band recorded in the '70s.

Tommy Dunbar, the founder of the Rubinoos, filed the suit in California's Northern Federal District Court in San Francisco on July 2. The suit alleges that "Girlfriend" bears striking similarities to the Rubinoos' song "I Wanna Be Your Boyfriend," co-written by Dunbar and former Rubinoos' road manager James Gangwer, and released by Beserkley Records in 1978.

The lawsuit also names as defendants Lavigne's publishing company Avril Lavigne Publishing and the co-writer of "Girlfriend," producer/remixer Dr. Luke.

Dunbar and Jon Rubin formed the Rubinoos as middle school students in Berkeley, Calif., in 1973. The band is best known for its 1977 remake of the Tommy James and the Shondells' hit, "I Think We're Alone Now" which reached No. 45 on the Billboard Hot 100.

Lavigne's Vancouver-based manager, Terry McBride, CEO of Nettwerk Music Group, claims the suit "has no basis. There's nothing similar (between the two songs)," he says. "Our musicologist says there is no similarities of melody, choral progression or meter."

McBride, however, may settle the suit out of court if the costs of defending the case start to prove too high. He says, "You are forced to consider doing this because American lawyers can do these cases on contingency. If I defend and win, it costs me $300,000 U.S. If I go to get my costs back, the other party declares bankruptcy. You end up footing the bill."

McBride adds, "Avril has insurance that covers off these sort of suits that are so prevalent in this business."