Former President Chun Doo-hwan is estimated to have accumulated about 933 billion won ($829 million) in illegal wealth, the main opposition party said Friday, stepping up calls for him to pay his long overdue fines.

Chun, who ruled from 1981-88, was ordered by the Supreme Court in 1997 to return 220 billion won he was found to have accumulated illegally to the state coffers. He refused to make the payment, saying he was almost penniless.

The former president has so far paid only a quarter of the total, with some 167.2 billion won remaining unpaid.

The main opposition Democratic Party (DP) has proposed a series of bills aimed at collecting the fines before the statute of limitations expires in October.

"(Chun) took 100 billion won from (the presidential office) Cheong Wa Dae as he left office in 1988, and is suspected of receiving another 500 billion won in bribes from 30 heads of conglomerates," Rep. Jun Byung-hun, the DP floor leader, said at a Supreme Council meeting as he disclosed the party's estimates of Chun's illegal wealth.

The remaining 333 billion won has been disguised as property and wealth belonging to family members, including his three sons, Jun said.

Meanwhile, Chun's successor, former President Roh Tae-woo, has expressed his intention to pay the remainder of his unpaid fines, according to officials at the Supreme Prosecutors' Office.

Roh's wife, Kim Ok-suk, filed a petition with the Supreme Prosecutors' Office and the Seoul Central District Prosecutors'

Office on Thursday, asking it to make Roh's younger brother, Jae-woo, and a former in-law return their wealth so that they could pay the remainder of their fines, the officials said.

Roh was ordered by the Supreme Court in 1997 to pay about 263 billion won in fines for bribe-taking and other offenses.

He has 23 billion won left to be paid. (Yonhap News)