A former Navy chief is under investigation over suspicions that he took bribes from a now troubled shipbuilding conglomerate four years ago in return for business favors, state investigators said Tuesday.

Sources at a government anti-corruption task force said they were investigating whether retired Adm. Jung Ok-geun played any role in STX Group's provision of 700 million won (US$648,000) to a yacht company in a sponsorship deal in October 2008.

The group's two subsidiaries, which produce high-speed ships and engines for naval vessels, paid the money to the yacht company, whose majority stake was owned by the eldest son of the then Navy chief Jung, they said.

The yacht company went out of business shortly thereafter, raising suspicions that it may have been a paper company, according to the sources.

The sources also said investigators are questioning the current head and a former executive member of STX to find out more about these suspicions.

They plan to summon the former head of STX Group, who is currently serving a jail sentence, and possibly the former Navy chief himself if they collect enough incriminating evidence.

In late October, Kang Duk-soo, who headed the group from 2003 to February 2014, was sentenced to six years in jail for embezzlement and malpractice.

Last November, the government launched the task force of prosecutors, military officers and state officials to uproot corruption in the defense industry.

The move came after an expensive indigenous Navy salvage ship failed to rescue those missing from a ferry disaster in April, which claimed more than 300 lives. (Yonhap)