SEOUL - Republic of Korea President Moon Jae-in and his US counterpart Donald Trump on Sunday pledged to work closely to ensure the success of the planned summit between Trump and the Democratic People's Republic of Korea top leader Kim Jong-un.

The two leaders exchanged their views on the recent responses from the DPRK when they held talks via telephone for 20 minutes, according to the ROK's presidential office.

Moon is scheduled to visit Washington next week to hold a meeting with Trump to discuss the summit, among other issues.

The Moon-Trump talks will hopefully serve as a bridge to a successful DPRKUnited States summit, the presidential National Security Office said on Friday.

On Wednesday, Pyongyang said it may reconsider the scheduled US-DPRK summit because of extremely provocative remarks by US officials.

Kim Kye-gwan, the DPRK's first vice-foreign minister, said in a statement that the Trump administration must show sincerity in its desire to meet with the DPRK to improve bilateral relations.

Before the statement, the DPRK threatened earlier in the day to withdraw from the scheduled meeting with the US next month due to ongoing US-ROK joint war games, which kicked off on May 11.

Chinese Foreign Ministry spokesperson Lu Kang said on Friday that China will continue to encourage the US and the DPRK to build mutual trust, and make joint efforts to promote the political resolution of the Korean Peninsula issue.

Kim and Trump are scheduled to meet in Singapore on June 12 for the first-ever DPRK-US summit.

Meanwhile, the DPRK has demanded the return of a group of women that it said were abducted two years ago by ROK intelligence officers.

The return of the restaurant workers is key part in settling humanitarian issues in the joint declaration by the leaders of the two sides last month at an inter-Korean summit in Panmunjom, the Korean Central News Agency quoted a spokesman for the Central Committee of the Red Cross Society of the DPRK as saying on Saturday.

According to the spokesman, ROK cable broadcaster JTBC recently reported that claims the group defected in April 2016 were proven to be a conspiracy concocted by former ROK president Park Geun-hye.

The spokesman claimed the women had been "forcibly abducted", adding that how the ROK tackles the case "will have great impact on deciding the prospect of settling the humanitarian issue between the north and the south clarified in the Panmunjom Declaration".

Twelve DPRK women were abducted two years ago from a third country where they were working to the ROK, said Pyongyang.

Xinhua