North Korea increased its shipment of natural resources to China as it suffered from international sanctions and isolation stemming from its weapons programs, South Korean data showed.

The North’s external trade surged 51 percent last year to a 22-year high of $6.3 billion thanks to robust Chinese demand, according to the state-owned Korea Trade-Investment Promotion Agency.

Pyongyang’s exports, chiefly consisting of natural resources, soared 84 percent to $2.79 billion. Imports rose 32.6 percent to $3.53 billion. Its key exports were coal, iron ore and textiles. It primarily imported crude oil, grains and machinery.

The increase reflects the North’s scramble for foreign currency to fund the April centenary celebrations of the birth of its founder, Kim Il-sung.

Trade deficits fell more than 35 percent to $740 million on-year in 2011 from $1.15 billion a year ago, the South Korean trade agency said.

“In the past, North Korea was not as eager as now to export to China and mainly imported from there because it could earn dollars from other methods such as inter-Korean exchanges,” said Dong Yong-seung, a North Korea specialist at Samsung Economic Research Institute in Seoul.

But the figures also mark the North’s growing reliance on China, its sole major ally and donor. Trade with China went up 62.4 percent on-year to $5.63 billion, taking up nearly 90 percent of total. The ratio has steadily risen from 52.6 percent in 2005 to 83 percent in 2010.

Russia remains Pyongyang’s second-largest trade partner with $110 million last year. Others include Germany, India, Bangladesh, Taiwan, Indonesia and Thailand.

The North Korean economy is grappling with a barrage of sanctions triggered by the communist regime’s unwavering devotion to atomic weapons, frequent saber-rattling and a botched rocket launch in April.

Frozen relations with Seoul, Washington and other countries precipitated a sharp cut in crucial assistance, exacerbating food and fuel shortages and driving more people to cross the border.

By Shin Hyon-hee (heeshin@heraldcorp.com)