K-pop boy group EXO's Baekhyun, Xiumin and Chen have lodged a complaint with the antitrust regulator against their agency SM Entertainment's "unfair" contract terms, their lawyer said Monday.

The members of the nine-piece group have been in a dispute with the K-pop powerhouse over their excessively long contract durations and the agency's alleged lack of transparency in financial settlements.

They notified the agency through their lawyer last week of their decision to terminate their contracts, which the company said were renewed in December, citing those reasons.

On Sunday, the singers took their grievance to the Fair Trade Commission in line with their previous warning, according to their lawyer.

"On behalf of my clients, I submitted a complaint to the Fair Trade Commission against SM Entertainment yesterday," Attorney Lee Jae-hak from the Seoul-based law firm Lin said in a press release.

He added his side is seeking the authorities' intervention in "the company's act of abusing its dominant position in business."

The complaint addresses several issues, including the agency's policy of establishing the debut date as the starting point for exclusive contracts, which were signed prior to the debut itself. It also questioned the relatively long contract durations for SM artists compared to those managed by other K-pop agencies.

The complainants argue that despite receiving two corrective orders from the antitrust watchdog in 2007 and 2011, the company continued to implement the disputed terms. Baekhyun unveiled part of his contact with the firm to back up his claim.

"If the minimum number of albums (specified in the contract) is not released, the contract period automatically extends until the requirement is met, and there is no specified upper limit on the duration," they said. "This is clearly a slave contract."

SM also released a press statement vowing to conditionally provide copies of the trio's settlement materials as they have demanded.

"After careful consideration, we decided to provide the copies on the condition that the three and their agents do not use them for any unfair purpose other than checking the content," the company said. "We also explained this situation to other EXO members and asked for their consent or understanding."

SM, however, refused to accept the trio's demands for the termination of their contacts.

"We want to make it clear that a contract should not be terminated only with a unilateral notification," it said.

The company added it will continue discussing the matter with the three artists to prevent any disruption to the band's future activities. (Yonhap)