An indie pop singer has filed a copyright violation lawsuit against Justin Bieber, saying the superstar stole the distinctive vocal riff in his hit "Sorry" from her.

Casey Dienel -- who performs under the stage name White Hinterland and has won acclaim in indie music circles -- said she was entitled to "substantial" profits from Bieber's song, saying the amount should be determined at a jury trial.

"Ring the Bell," a track from White Hinterland's third album "Baby," released in early 2014, opens with a repeated four-note progression in her airy voice before synthesizers come in.

"Sorry," from the Canadian celebrity singer's album "Purpose," which came out in November, is also built on a repeated vocal riff interspersed with a dance beat.

"An ordinary lay listener would instantly recognize the sample and similarity between the songs," said the lawsuit filed this week in a federal court in Nashville.

The complaint alleges that the riff is so similar -- moving from the notes of B-flat to C to E-flat to F -- that Bieber's team took "Ring the Bell" as a sample and distorted it electronically without her permission.

Dienelsaid she repeatedly tried to contact Bieber's team to no response.

Bieber did not immediately comment on the lawsuit.

The suit also names Bieber's songwriters as defendants, including Skrillex, a leading electronic music producer.

Skrillexand Diplo, another prominent producer, helped Bieber craft a new tropical house sound for "Purpose," the third top-selling album in the United States last year.

Some fans interpreted "Sorry" -- with its refrain "Is it too late now to say I'm sorry?" -- as the former child star's apology of sorts for his past antics or a message to his ex-girlfriend, fellow singer Selena Gomez.

The 22-year-old has had a string of legal run-ins for incidents including throwing eggs at a neighbor's house, driving under the influence of alcohol without a license and allegedly assaulting a photographer.

The number of copyright cases against major musicians has been growing in recent months.

Last year, a Los Angeles jury ordered pop stars Robin Thicke and Pharrell Williams to pay more than $7 million to the estate of the late Marvin Gaye over their hit song "Blurred Lines."

Dienel, who was raised in Massachusetts and lives in the indie rock capital of Portland, Oregon, was initially known for jazzy, piano-backed pop but has increasingly brought in electronic elements.