Families of Japanese abducted by North Korea to train their spies have made an emotional appeal for the issue to be tackled at the forthcoming US-Pyongyang summit.

At least 17 citizens were understood to have been abducted in Japan by North Korea in the 1970s and the 1980s in order to teach their agents Japanese language and culture.

Relatives have campaigned tirelessly for their return for decades, with hopes of a breakthrough recently raised by a proposed summit between US President Donald Trump and North Korean leader Kim Jong-un.

A group of relatives made a request directly to William Hagerty, the US ambassador in Japan, for the issue to be resolved at a top level, during a visit to his residence in Tokyo.

“We would like to ask President Trump to strongly urge North Korea to return the abductees,” Shigeo Iizuka, head of the group representing the relatives of the abductees, told the ambassador. "We need his help to push for specific measures so that the victims can come home."