A co-leader of South Korea's second-largest opposition party on Friday called for nullifying a landmark deal struck between Japan and South Korea last year on the issue of "comfort women" forced into wartime Japanese military brothels.

Chun Jung-bae of the People's Party, which almost doubled its parliamentary strength in the April 13 national election, made the assertion in a meeting with Japanese Ambassador Koro Bessho, Yonhap news agency reported.

He was quoted as saying the issue should be resolved with Japan's legal responsibility recognized first, while suggesting Bessho meet with former comfort women.

Bessho reportedly said the bilateral agreement is a crystallization of the wisdom of the Japanese and South Korean governments that made maximum efforts to settle the issue and it is therefore important to implement it in a sincere manner.

In the landmark deal struck last Dec. 28, Japan and South Korea agreed to resolve the comfort women issue "finally and irreversibly."

Under the agreement, the Japanese government admitted its responsibility over the issue and the involvement of the Japanese military.

The main opposition Minjoo Party of Korea is also opposed to the Japan-South Korea deal, calling for renegotiation.