The ratio of national debt to gross domestic product (GDP) in South Korea reached 34 percent last year amid growing sales of government bonds, the Finance Ministry said Tuesday.

The ratio of the country's national debt to GDP reached 34 percent in 2011, up 0.6 percentage points from a year earlier, according to the Ministry of Strategy and Finance. The national debt includes both central and local governments'borrowing.

In value terms, the national debt amounted to 420.7 trillion won (370 billion U.S. dollars) in 2011, up 28.5 trillion won from a year before.

The central government debt, excluding local government borrowing, expanded 29 trillion won to 402.8 trillion won last year, sending the debt-to-GDP ratio to 32.6 percent, up 0.7 percentage points from the previous year.

Last year's debt growth was mainly attributed to an increase in government bond issuance, which amounted to 397.1 trillion won in 2011, up 29.9 trillion won from a year before.

Meanwhile, the nation's consolidated fiscal balance saw a surplus of 18.6 trillion won in 2011, but the managed fiscal balance, excluding social security funds, posted a deficit of 13.5 trillion won. Social security funds include national pension funds, industrial accident compensation funds and employment insurance funds.

The South Korean government's total tax income, including non- tax revenue, amounted to 270.5 trillion won in 2011, while total tax expenditure came to 258.9 trillion won, sending last year's tax balance to a surplus of 11.6 trillion won.