National Assembly Speaker Woo Won-shik has expressed deep regret over the government agreeing to the UNESCO World Heritage registration of Japan's Sado mines, calling the government’s move “very wrong.”

Woo revealed the stance in a statement released on Tuesday while urging the government to fully disclose the diplomatic negotiations it held with Japan on the issue. 

He then said the responsibility to shed light on suspicions surrounding Seoul’s handling of the registration process lies with the National Assembly. 

Woo said if the government agreed to the registration of the mines as part of measures to improve Seoul-Tokyo ties, it has committed a grave error, saying issues regarding history and human rights cannot be bargained with and are far from developing future-oriented Seoul-Tokyo relations. 

On controversy regarding the absence of the expression "forced labor" in an exhibition of Japan's Sado mines, Woo said if Seoul agreed to the registration process without knowing such fact, that would signify a failure of diplomatic negotiations. He said that it would be a bigger problem if Seoul had been aware of the omittance.