TOKYO (Reuters) - Prime Minister Shinzo Abe said on Friday (March 30) he would explain Japan's stance on the North Korean abduction of Japanese citizens in a meeting with Donald Trump, ahead of the US president's planned summit with North Korean leader Kim Jong Un.

Japan's government worries the emotive matter of the abductees, which Abe has made a key issue during his political career, will take a back seat to nuclear and missile issues in the US-North Korean summit.

"I plan to visit the Unites States next month and have a summit meeting with President Trump and discuss the North Korean situation," Abe said.

"In particular I would like to explain Japan's stance on the abduction issue," he said during a meeting with family members of those abducted by North Korea decades ago.

North Korea admitted in 2002 it had kidnapped 13 Japanese in the 1970s and 1980s to train as spies, and five of them returned to Japan. Tokyo suspects that hundreds more may have been taken.

North Korean leader's Kim Jong Un met President Xi Jinping in China this week, his first trip abroad since becoming North Korean leader in 2011.

South Korean President Moon Jae In is set to meet Kim Jong Un on April 27, followed by a planned summit with Trump in May, to try to resolve the crisis over Pyongyang's nuclear and missile programmes.

Japan wants to make sure Trump does not make a deal with Pyongyang that protects the US mainland but leaves Japan vulnerable.

Japanese officials including Abe have left open the possibility that Abe may hold talks with Kim Jong Un, with a focus on the abductions, although diplomatic experts say that would likely be after seeing how the other summits play out.

"The missile and nuclear issues need to be negotiated among the parties concerned, especially between the United States and North Korea," a former Japanese diplomat said on condition of anonymity.

"We need to negotiate on bilateral issues and the abductions are the main thing."