The former chief of the country's top steelmaker, POSCO, appeared before prosecutors Wednesday to face questioning over alleged corruption.

Chung Joon-yang showed up at the Seoul Central Prosecutor's Office in southern Seoul to undergo interrogation for the second time since last week.

For the past six months, the prosecution has been investigating suspicious deals and alleged slush funds created while Chung headed the firm from 2009 to 2014.

Prosecutors said they will grill Chung on whether he is involved in giving work to the firm's subcontractor, T.M Tech Ltd., which is owned by a close acquaintance of former President Lee Myung-bak's older brother.

In the previous summons, Chung was asked about a deal in 2010, in which POSCO bought a stake in local plant equipment maker Sungjin Geotec Co. for nearly 160 billion won ($141 million). 

Jeon Jung-do, head of mid-sized manufacturer Sehwa MP and the biggest shareholder of Sungjin Geotec, allegedly profited substantially from the stake purchase, prosecutors said. Chung and Jeon are known to be friends.

Also, engineering firm Dongyang Construction is suspected of creating slush funds for POSCO and its affiliates while winning bids for about 10 overseas projects placed by POSCO since 2009, prosecutors said.

The chairman of Kosteel Co., which buys steel slabs from POSCO to make wire rods, is suspected of helping the global steel giant evade taxes by doctoring transaction records. The Kosteel chairman is also known to be a close friend of Chung. (Yonhap)