SEOUL, Dec. 16 (Yonhap) -- The chairman of SK Group will be summoned next week for interrogation over allegations that he embezzled a massive amount of company funds in collusion with his younger brother, prosecutors said Friday.

Prosecutors have given notice to Chairman Chey Tae-won to appear at the prosecutors' office in southern Seoul around 9:30 a.m. on Monday for questioning, they said.

Chey had initially been scheduled to undergo interrogation last week, but prosecutors postponed the summons so they could better prepare.

The chairman of the country's third-largest family-controlled conglomerate and his younger brother and vice chairman, Jae-won, are suspected of embezzling a massive amount of company funds. The sum was previously speculated to be as high as 100 billion won ($86.6 million)

The embezzled funds were reportedly part of a total of 280 billion won set aside by 18 SK affiliates for investment purposes and used to make up for as much as 300 billion won in losses incurred as a result of the 51-year-old chairman's unsuccessful stock futures investments.

The younger brother, who is suspected of having orchestrated the scheme, reportedly partly admitted to the alleged embezzlement in two previous rounds of questioning this month.

SK Group controls dozens of affiliates in various industrial segments, including top oil refiner SK Innovation and No. 1 wireless service provider SK Telecom.