South Korea's richest man has been hit with a second lawsuit by a close relative relating to his inheritance of shares in companies that are part of the Samsung Group, the country's largest conglomerate.

The lawsuit from 70-year-old Lee Kun-hee's sister was filed in Seoul Central District Court on Monday and comes as Samsung confronts a tricky succession to the third generation of the family that founded a company that is synonymous with the success of Korea Inc.

Lee is chairman of Samsung Electronics with a fortune estimated at $9.3 billion by Forbes magazine.

His elder sister, Lee Sook-hee, is demanding that he return assets worth about 190 billion won ($168.27 million), some shares in Samsung Life Insurance and Samsung Electronics as well as cash that she says were rightfully her inheritance from her father, a spokesman for the court told Reuters.

The law firm representing the sister, Hwawoo, confirmed the suit but declined to comment further.

Hwawoo is also representing Lee's elder brother in a similar suit filed earlier that is seeking 710 billion won in compensation, according to Korean media reports.

A spokeswoman for parent Samsung Group declined to comment directly on the suits against Lee.

We understand that the matter of inheritance has long since been settled, she said.

Lee took over the helm of Samsung Group in 1987 and has been indicted for tax evasion, but was pardoned by the president. He is still involved in running Samsung Electronics, the world's largest technology company by revenue.

His son, Lee Jae-yong, who is now president and chief operating officer of Samsung Electronics, is believed to have been groomed to take over the company.

The lawsuits have come as South Korea faces parliamentary and presidential elections in the same year for the first time in 20 years and the role of the country's conglomerates, or chaebol, has come under close scrutiny from opposition politicians who say they have enriched themselves excessively.

A top opposition politician told Reuters recently that if his party took power, it would seek to rein in the power of the chaebol. The top 30 Korean chaebol have net profits equivalent to 40 percent of total government spending, according to official data.

(Reporting by Ju-min Park; Additional reporting by Hyunjoo Jin; Editing by David Chance and Nick Macfie)