SEOUL, Jun. 12 (Reuters) - South Korea's main opposition leader was indicted on Wednesday on bribery charges in an alleged scheme to use an underwear maker to transfer funds to North Korea and facilitate a visit to Pyongyang when he was a provincial governor, news reports said.

Democratic Party leader Lee Jae-myung's deputy when he was Gyeonggi province governor had already been found guilty of bribery and transferring illegal funds in a conspiracy involving Ssangbangwool Group to send $8 million to North Korea.

Ssangbangwool is a business group that began as an underwear maker and later expanded to other businesses.

Calls to the public affairs office at the Suwon District Prosecutors' Office went unanswered.

Lee has denied any involvement or knowledge of the scheme, which dates to 2019 and 2020 and was aimed at promoting a commercial project with North Korea and a visit by Lee to Pyongyang, which would have burnished his status as a rising political figure.

"I am not that foolish," Lee said last year, calling the charges against him "fiction" as a court denied a warrant for his arrest.

After the indictment on Wednesday, he said: "The prosecutors' creativity is getting worse."

Lee was the Democratic Party's candidate for president in 2022, and he narrowly lost to Yoon Suk Yeol, a career prosecutor. Lee is considered a major contender for the next presidential election in 2027.

He is on a separate trial on corruption charges stemming from his term as a mayor of a city near Seoul.

The first summit between North and South Korea in 2000, which was credited with starting a period of engagement, was tarnished after government officials were convicted for transferring funds to Pyongyang through the Hyundai Group, which subsequently had nearly exclusive rights to major business ventures in the North.