Prosecutors said Thursday they plan to seek international legal cooperation as part of efforts to locate concealed assets of former President Chun Doo-hwan, who owes a massive fine to the state.

Chun was ordered by the nation's top court in 1997 to return to the state coffers 220 billion won ($196.8 million) that he was found to have illegally accumulated during his term from 1980 to 1988.

The former dictator, however, has so far paid only a quarter of the total, with some 167.2 billion won remaining unpaid. He refused to make the payment, saying he was nearly penniless.

A task force within the Seoul Central District Prosecutors' Office said it plans to make requests to judicial and financial authorities in Singapore, the British Virgin Islands and the U.S. for cooperation in tracking down Chun's hidden assets overseas.

The prosecutors' office suspects that Chun borrowed names of his immediate family members, relatives and close aides to set up shell companies and open bank accounts overseas with an aim to hide massive slush funds that he has stashed away.

Noticeably, the prosecution said it was mulling over requesting Singaporean authorities for information on bank accounts allegedly owned by a shell company of Chun's eldest son, Chun Jae-kook.

The paper company, established by the younger Chun in the British Virgin Islands in 2004, has several bank accounts under its name at a Singaporean branch of Arab Bank, the prosecution said.

The prosecution also said it is paying close attention to the fact that more than $1 million has been deposited to the bank accounts.

The requests for information will be made through a legal cooperation channel with related countries, it said.

Meanwhile, the prosecution said it has also banned some 40 people, who have close ties to the former president, from leaving the country as part of the probe.

People under the travel ban include those who have acted as proxies to purchase expensive artwork and properties for the former president and his family, the office said, refusing to disclose their identities.

In December 1979, Chun, then an army major general, led a military coup and filled a power vacuum created by the assassination of former President Park Chung-hee, the father of the current president, Park Geun-hye. (Yonhap News)