China's transport container manufacturers earned 1.82 billion U.S. dollars from exports in the first quarter, double the figure from the same period of last year, according to the General Administration of Customs.

The export volume went up 86.1 percent to 600,000, with Hong Kong, the European Union, the United States and Japan as the major markets.

With a new production line with an annual output of 150,000 standard containers (twenty-foot equivalent units or TEUs), the largest in the country's main production base Guangdong Province, opening in Nansha in March, the country's container output is expected to expand further.

Customs figures show only 42,000 containers, or 7.1 percent, were completely domestically sourced and manufactured. The remaining 92.9 percent of the container exports were processed with materials supplied by clients and thus involved a lower value added.

With an annual production capacity of two million TEUs, China holds 90 percent of the world's container market, but relies on imports for more than half of the steel plate less than two millimeters thick, a primary raw material for best quality containers.

A Customs statement issued on Wednesday said container manufacturers must improve their metallurgical technology, diversify their products and shift production from low-end standard containers to large sizes or special purpose containers.

The average price for a 20-foot standard container went up by 11.3 percent to 1,940 U.S. dollars in the first quarter and for a 40-foot container by 18.9 percent to 4,483 U.S. dollars. The prices for larger containers ranging from 45 to 53 feet averaged 6,474 U.S. dollars, up 18.2 percent.