SEOUL (BLOOMBERG) - North Korea's state news agency slammed Japan for insisting on the return of abductees as a condition of normalising ties, accusing its neighbour of going "against the trend" towards the "building of a bright future" in the run-up to an unprecedented summit between US President Donald Trump and North Korean leader Kim Jong Un.

"The reactionaries of Japan are hyping the 'issue of abduction' which had already been settled," KCNA said in a commentary published on Saturday (May 12). "This is just a mean and foolish behaviour to stem the trend of peace on the Korean peninsula," it added.

Japanese Prime Minister Shinzo Abe has repeatedly insisted the return of Japanese citizens abducted by North Korea decades ago must be achieved alongside the abandonment of nuclear weapons and ballistic missiles before a settlement can be reached. He has pressed Mr Trump to raise the issue at his summit with Mr Kim.

The Japanese government says at least 17 of its citizens were abducted by North Korea in the 1970s and 1980s. Five were returned in 2002 and Japan says it is not satisfied with North Korea's explanations about the fate of the others.

KCNA said Japan was in the "wretched plight" of being alienated from developments surrounding the Korean peninsula, something the Abe government denies.

Mr Abe has sought to strengthen ties with Mr Trump in a bid to ensure that his concerns about the abductees and about mid- and short-range missiles that threaten Japan and not the United States are addressed.

Mr Trump may visit Japan immediately after his summit with Mr Kim in Singapore on June 12 to draw attention to the strength of the alliance, the Nikkei newspaper reported on Sunday.

At Mr Abe's summit with Chinese Premier Li Keqiang and South Korean President Moon Jae In in Tokyo last week, the three agreed on the need to denuclearise North Korea, but there was no mention of the policy of "maximum pressure" that Japan had sought to maintain.