South Korea has started a legal process to extradite a Chinese man who attacked Japan's embassy in Seoul to Tokyo, officials said Friday, in a case that has strained Sino-Japanese relations.

Liu Qiang is serving a 10-month jail term for hurling four petrol bombs at the mission in January in an attack which left burn marks on its outer wall. Tokyo has asked South Korea to hand him over for trial, while Beijing wants Seoul to deport him to China.

Justice ministry officials said they would ask an appeals court to decide whether Liu should be extradited to Japan.

The Chinese foreign ministry spokesman Hong Lei on Friday said Beijing "attaches great importance to this case".

"We hope and believe that (South Korea) will handle this case in a fair and appropriate manner," he said.

Liu told investigators that he attacked the embassy because he was angry at Tokyo's refusal to deal with the issue of "comfort women" forced to work in Japanese military brothels in World War II.

He said his late maternal grandmother, who was Korean, was forced into wartime sex slavery in China.

Some 200,000 women from Korea and other countries were drafted to work in Japanese army brothels, according to historians. Japan has rejected talks on compensating them.

Liu also claimed responsibility for an arson attack which caused minor damage at Japan's controversial Yasukuni shrine last December.

The shrine in Tokyo is dedicated to 2.5 million Japanese killed in wars, including key war criminals, and is often seen as a symbol of the country's wartime aggression.