U.S. President Donald Trump has promised that the issue of North Korea's past abductions of Japanese nationals will be raised "100 percent" in his meeting with North Korean leader Kim Jong Un, Prime Minister Shinzo Abe said Monday after speaking on the phone with Trump.

As the United States stepped up last-minute preparations for the much anticipated U.S.-North Korea summit in Singapore on Tuesday, Abe and Trump reaffirmed their basic policy on North Korea.

Trump "guaranteed 100 percent" that the abduction issue will be raised, Abe told a gathering in Tokyo after the phone call.

The prime minister has been asking Trump to urge the North Korean leader to resolve the issue of the abductions that took place in the 1970s and 1980s, saying recently he also wants to meet with Kim to seek an early resolution. The issue has prevented the two countries from establishing diplomatic ties.

"I believe that Japan and the United States, along with South Korea, have completely...agreed on the basic policy (for the summit)," Abe told reporters at the prime minister's office.

"I hope that the (U.S.-North Korea) summit tomorrow will become a historic summit and a major step toward peace and stability in Northeast Asia," he said.

Japan has dispatched a team of senior government officials to Singapore in an effort to keep abreast of developments related to the summit at which North Korea's denuclearization will be the main item on the agenda.

During a parliamentary session on Monday, Foreign Minister Taro Kono revealed the Japanese and U.S. leaders plan to speak on the phone after Tuesday's summit.