SK Group, South Korea's No. 3 conglomerate, said Thursday that its affiliates plan to invest a combined 17 trillion won ($14.7 billion) this year, up 21 percent from last year, although economic uncertainty still persists at home and abroad.

Energy and telecom giant SK said its 16 affiliates will newly hire 8,200 this year, up 200 from last year.

SK's aggressive investment plan is accelerating as group chief Chey Tae-won came back to the management last year.

In 2014, the group chief stepped down from all key posts at the group's affiliates as he was convicted on charges of spending corporate funds for personal use. He was sentenced to four years in prison but was released with a special pardon in 2015.

The group said of the earmarked spending, some 5 trillion won will be spent to merge with other rivals, up from 3.1 trillion won spent last year.

Early this week, SK Holdings Co., the group's holding firm, has decided to buy a controlling stake in LG Siltron Co., a local producer of wafers used in semiconductor manufacturing, for 620 billion won, as part of efforts to expand its chipmaking business presence.

SK Group has been beefing up its presence in the chipmaking sector by taking over Hynix Semiconductor Inc., currently SK hynix Inc., in 2011. In 2015, the group also bought OCI Materials, a local manufacturer of special gases used in chipmaking, LCD and solar panels, for 482 billion won.

SK hynix, a chipmaking unit, will spend 7 trillion won, while oil refiner SK Innovation eyes 3 trillion won.

In August last year, SK hynix said it will spend 46 trillion won over the next 10 years to build three new semiconductor production lines in an effort to bolster its market position and join government efforts to revitalize the economy.

SK Telecom, the country's top mobile operator, also said it will spend 11 trillion won over the next three years. (Yonhap)