EXO's Baekhyun, Xiumin and Chen notified SM Entertainment that they are terminating their contracts with the agency due to mistreatment and unfair contract terms, their lawyer said Thursday.

SM Entertainment has been refusing to provide papers on how the EXO members have been given their payment from the moment of their debut, even after the singers requested seven times, their attorney Le Jae-hak said.

"It is the artist's most basic right to demand clear and precise proof of how payment has been made, and SM Entertainment is required to abide by the law," Lee said. "But SM Entertainment maintains that such data cannot be shared."

Lee noted that the agency also offered singers 12- to 13-year contracts, which is longer than the standard 7-year contract recommended by the government.

A standard contract is usually based on seven years, and an artist has the right to terminate the contract if it surpasses the 7-year threshold.

"The artists have been asking very firmly for the payment data until Wednesday but have resorted to demanding a termination of the contract as of Thursday upon the company's refusal to do so," Lee added.

EXO is a nine-member boy band that debuted in 2012 under SM Entertainment and is one of the most popular third-generation K-pop boy band.

BY YOON SO-YEON [yoon.soyeon@joongang.co.kr]