South Korea renewed its pledge Thursday that it will make various efforts to induce China to play a constructive role over North Korea's nuclear weapons program.

"We expect China and Russia to play a constructive role," presidential spokesman Jeong Yeon-guk told reporters.

He also said South Korea will closely work with relevant countries to ensure that the U.N. Security Council can adopt a resolution for strong and effective sanctions on North Korea over its fourth nuclear test earlier this month.

China and Russia are two of the five permanent veto-wielding members of the council.

The two countries have also been involved in long-stalled six-nation talks aimed at ending North Korea's nuclear weapons program in return for political concessions and economic aid. The nuclear talks -- which also include the two Koreas, the U.S. and Japan -- were last held in 2008.

On Wednesday, China expressed disapproval of the U.S.-led drive to slap the toughest-yet sanctions on North Korea for its nuclear test.

Chinese Foreign Minister Wang Yi said after talks with U.S.

Secretary of State John Kerry in Beijing that China agrees that the council needs to take further action and pass a new resolution, but sanctions shouldn't be the objective.

China is believed to have significant leverage over North Korea as more than 90 percent of North Korea's trade comes from China.

Still, China is apparently against going too far on North Korea out of the concern that strong sanctions could destabilize North Korea, which in turn could hurt Beijing's national interests. (Yonhap)