Japanese Prime Minister Yasuhiro Nakasone told Chinese government heavyweight Hu Yaobang in 1986 that Japan was prepared to trade with North Korea, according to Japanese diplomatic records declassified Wednesday.

Despite a lack of diplomatic relations between Tokyo and Pyongyang, Nakasone told Hu that Japan was prepared for bilateral trade, according to the records.

Nakasone also aimed to help improve relations between China and South Korea at the same time, the document states, showing how Nakasone tried to leverage his friendly relationship with Hu to work with China in pursuit of peace on the Korean Peninsula.

On a November 1986 visit to China, Nakasone told Hu of South Korea's desire to formally establish relations with China. While trying to serve as a bridge between Beijing and Seoul, Nakasone proposed at the same time improving ties between Japan and North Korea.

Hu, who was general secretary of China's Communist Party for much of the 1980s under the rule of Deng Xiaoping, was known for his support of reforms and warmth toward Japan.

But Hu said he could not fulfill either request.

The effort was covered to some extent by Japanese media at the time, with Kyodo News describing a "failure to work as a bridge between China and South Korea."

China and South Korea ended up establishing relations in 1992, while Japan and North Korea remain isolated from each other to the present day.

Nakasone and Hu met in Beijing's Great Hall of the People on Nov. 8, 1986. According to a declassified cable dated the following day, Nakasone told Hu he was asked to pass on South Korean leaders' message that "even if we cannot attain diplomatic relations with China, we want to expand (bilateral) exchange."

He also communicated Seoul's wish for bilateral trade with China and the mutual appointment of trade representatives.

Nakasone made clear that if Beijing and Seoul set up a trade framework, his administration was "prepared to carry out something similar between Japan and North Korea."

Hu replied that it would be hard to make such a thing happen between Japan and North Korea but vowed to convey the idea to Pyongyang and test its response, according to the file.

While Hu said South Korea's desire to improve relations with China was "a good thing," he effectively turned down the request by saying China would "need it to be accepted by North Korea and the other socialist countries."

According to the records, Nakasone also told Hu of South Korea's wish to hold four-party talks with China, the United States and North Korea.

Hu responded that the North and South would need to loosely form a union in order for that to happen.

They said Hu indicated China was having a hard time dealing with North Korea, prompting anger from Pyongyang by suggesting the North could hold talks with South Korea and the United States.

The declassified records also show that Hu told Nakasone about internal affairs in China, revealing his plan to refresh the Communist Party leadership at its 1987 congress by "making the old-timers quit."

Hu also criticized the Soviet Union in front of Nakasone for "lacking common vocabulary" with China on foreign policy, and revealed that East German leader Erich Honecker had told senior Chinese officials that the Soviet Union "should give back" a chain of islands seized from Japan after World War II.

Nakasone held talks with Honecker in East Germany in January 1987.

The row over the sovereignty of the islands off Hokkaido, called the Northern Territories in Japan and the Southern Kurils in Russia, continues to the present day.