The Constitutional Democratic Party of Japan and the Democratic Party for the People shelved their merger talks Tuesday as the two major Japanese opposition parties failed to narrow gaps.

The DPFP called for continued talks, but the CDPJ responded that further concessions are not possible.

The two sides "failed to narrow differences due to their own reasons," CDPJ Secretary-General Tetsuro Fukuyama told reporters after a meeting with his DPFP counterpart, Hirofumi Hirano.

The CDPJ and DPFP will continue to promote parliamentary cooperation among opposition parties while exploring the possibility of merging in the future.

The secretaries-general of the CDPJ and DPFP "will keep in touch with each other," Hirano said.

The suspension of the merger talks came as members were divided over the matter at both of the two parties.

At the CDPJ, Jun Azumi, the party's parliamentary affairs chief, has called for an early merger to better compete with Prime Minister Shinzo Abe's powerful ruling bloc.

But Hirotaka Akamatsu, a CDPJ member and vice speaker of the House of Representatives, has opposed any concessions to the DPFP over the name of a merged party and the selection of its senior members.

At the DPFP, leader Yuichiro Tamaki has placed great importance on preventing the party from breaking apart, as its members were split between those cautious about the merger and advocates.

JIJI Press