Chennai: The growth in debt levels over the decade-mainly driven by private debts makes emerging market economies vulnerable to external shocks, global credit rating agency Moody's Investors Service has said in a report. According to the report titled 'The Evolution of Emerging Markets External Debt: Private Sector Debt Drives Broad-Based Build-Up of Emerging Markets External Vulnerability Risks', the debt growth was highest in the Asia-Pacific region. The largest increase were reported in external borrowings in China, India, Indonesia, Taiwan and Malaysia, Moody's said. Driven by growth in private debt in China, India and Indonesia, debt levels in the Asia-Pacific region have grown at an average rate of 13.5 per cent, the report said. According to Moody's, the average external debt to gross domestic product ratio for Asia as a whole has recently increased from 31 per cent in 2008 to 47 per cent in 2015 -- well below the 78 per cent of Emerging Europe, but comparable to the 48 per cent in Latin America and the 43 per cent in the Middles East and Africa region. Total emerging and frontier market external debt -- defined as debt owed by residents of a country to non-residents -- has almost tripled from $3 trillion in 2005 to $8.2 trillion at the end of 2015. Debt is now growing faster than GDP and faster than foreign exchange reserves for many of these countries, said Moody's. "The increase in debt is being driven by the growth in private debt, rather than public debt. Since 2005, private sector external debt has grown at an annual rate of 14.3 per cent compared to 5.9 per cent growth rate for public sector debt," said Moody's. Moody's expects that global economic growth will remain sluggish for the medium term and commodity prices will stay low for several years going forward. This will affect foreign exchange revenues and reserve accumulation for commodity exporters. The potential for capital flows to slow, should US interest rates continue to rise, would also exacerbate the debt situation in emerging economies. "Even though developments differ by the country, these trends show that emerging and frontier markets are now more susceptible to economy-wide crises than they were a few years ago," said Elena Duggar, an Associate Managing Director at Moody's. "While sovereign debt profiles have improved, the increase in private sector debt is making sovereigns more vulnerable to contingent liabilities," Duggar added.