South Korea's 10 biggest companies by assets paid more than 2 trillion won ($1.83 billion) in retirement allowance last year as they underwent tough restructuring amid a protracted economic slump, industry data showed Monday.

The conglomerates' 97 listed affiliates paid a combined 2.1 trillion won in retirement benefits in 2014, up 33.3 percent from 1.6 trillion won the previous year, according to the data compiled by corporate tracker Chaebul.com.

Their administrative costs, referring to expenses not associated with manufacturing or sales, rose 3.4 percent on-year to 114.7 trillion won over the cited period.

Retirement payments accounted for 1.8 percent of the administrative expenses, up 0.4 percentage point from a year ago.

Hanwha Group, the nation's 10th-largest family-controlled conglomerate, spent 241.8 billion won, up 172 percent on-year, as Hanwha Life Insurance Co. reduced its payroll 8.7 percent.

Eighth-largest Hyundai Heavy Industries Group, which has suffered a massive deficit of 1.7 trillion won last year alone, paid 54.6 billion won to outgoing employees, up 99.6 percent from 27.4 billion won.

No. 1 Samsung Group's retirement payment stood at 846.8 billion won last year, as its two insurance units, Samsung Life Insurance Co. and Samsung Fire & Marine Insurance Co., carried out strict downsizing efforts.

SK Group, GS Group, Lotte Group and Hanjin Group showed a drop in their retirement payments, with No. 3 SK Group's grants falling 0.7 percent on-year to 145.7 billion won. (Yonhap)