Debts of South Korea's major public companies grew 12.9 percent last year from the previous year due to increased spending of the energy and transportation sectors and a growth in the government-led real estate development projects, a government report showed Monday.

Debts owed by the country's major 27 public corporations reached 328.4 trillion won (290.62 billion U.S. dollars) as of the end of 2011, up 37.5 trillion won, or 12.9 percent, from a year earlier, according to the Ministry of Strategy and Finance.

The public corporations include the state-run enterprises such as Korea Electric Power Corp. (KEPCO), Korea Gas Corp. (KOGAS), Korea National Oil Corp. (KNOC) and Korea Land & Housing Corp. (LH) .

Last year's debt growth was mainly attributed to increased facility investment for the energy and transportation infrastructure and the government-led real estate development projects such as construction of rental homes, the ministry said.

Total assets held by public firms expanded 8.4 percent on-year to 496.4 trillion won in 2011, roughly in line with the debt growth, according to the ministry.

Meanwhile, combined sales by the key corporations reached 128. 6 trillion won in 2011, up 13.6 trillion won from a year earlier, but their net profits were in the red of 0.5 trillion won last year due to a hike in production costs amid higher oil prices and a limited increase in public service charges.

Dubai crude, South Korea's benchmark, averaged 105.98 dollars a barrel in 2011, up 35.6 percent from an average price of 2010. Service charges for electricity and city gas rose 3.7 percent and 8.2 percent each last year, but charges for heating services edged down 0.3 percent.