Japan's Foreign Minister Taro Kono has conveyed to U.S. Secretary of State Mike Pompeo Tokyo's desire for talks with North Korea to resolve a long-standing abduction issue, a government official said Saturday.

Kono's remarks indicate Japan's frustrations. Pyongyang, which earlier this year started to pursue diplomacy toward neighbors China and South Korea as well as the United States, has shown no interest in communicating with Tokyo.

"Japan has been determined to hold direct talks with North Korea and to take every step toward an early resolution of the abduction issue," Kono was quoted by the official as telling Pompeo during a meeting on Saturday in Singapore, where both men are attending meetings hosted by the Association of Southeast Asian Nations.

Prime Minister Shinzo Abe has called tackling the matter his "life's work." But Abe, who over recent years repeatedly said bolstering pressure on Pyongyang is vital to halting the country's nuclear and ballistic missile development programs, has in turn faced strong criticism from North Korea.

On Friday night, Kono chatted with North Korea's Foreign Minister Ri Yong Ho, and later told reporters that he informed Ri of Japan's views and basic stances. But Kono declined to disclose further details, suggesting the conversation may not have been held in an amicable atmosphere as ties between Japan and North Korea have been worsening.

Tokyo and Pyongyang remain at odds over the issue of Japanese abducted by North Korean agents in the 1970s and 1980s.

Japan officially lists 17 citizens as having been abducted, and suspects North Korean involvement in many more disappearances. North Korea insists the issue has already been resolved.

On Saturday, the ASEAN Regional Forum -- an annual security gathering involving foreign ministers from nearly 30 nations including China, Japan, South Korea, the United States and the ASEAN members -- took place in Singapore.

It is one of the very few multilateral events attended by North Korea's foreign minister almost every year.

During their meeting, Kono and Pompeo confirmed the importance of maintaining U.N. Security Council resolutions against North Korea until Pyongyang achieves complete denuclearization as pledged, the Japanese official said.

Amid skepticism over whether North Korea will take concrete measures toward denuclearization, Kono and Pompeo agreed to continue working together to pressure Pyongyang to give up all its nuclear weapons and ballistic missiles, the official said.

At a historic summit in June in the city-state, North Korean leader Kim Jong Un promised U.S. President Donald Trump to achieve "complete" denuclearization of the Korean Peninsula in return for security guarantees from the United States.

But negotiations between Washington and Pyongyang on the specifics of denuclearization appear to be at a standstill, while North Korea has been improving ties with China, Russia and some ASEAN countries.

On Friday, North Korean Foreign Minister Ri sought the easing of international sanctions on Pyongyang, according to an ASEAN diplomatic source.

Ri was quoted by the source as asking during a bilateral meeting with another country why U.N. sanctions have not yet been removed despite "much progress" being made on the nuclear issue.

The source added China and Russia have become willing to relax some sanctions, raising concern that the effects of the pressure campaign on North Korea will wane.

Kono and Pompeo also held trilateral talks involving Australian Foreign Minister Julie Bishop on Saturday.

The three ministers exchanged views on a plan to jointly set up a fund to invest in infrastructure projects in the Indo-Pacific region, the Japanese official said. The trilateral partnership is apparently aimed at countering China's growing influence.

Washington and Tokyo are cautious about China's "One Belt, One Road" initiative of connecting countries along the ancient Silk Road more closely, saying Beijing is trying to expand its security and economic influence in Asia, the Middle East, Europe and Africa.