The long-term trends also offer little solace for American officials. Chinese exports to the United States actually grew faster last month than imports from the United States. Rising Chinese imports tend to be in categories like oil from the Mideast as well as luxury goods and sophisticated machinery from Europe.

China’s General Administration of Customs said that exports rose 25.9 percent in April compared with a year earlier, to a record $155.69 billion, exceeding a previous record of $154.12 billion in December. The increase was somewhat surprising because the spring is traditionally a weak period for Chinese exports, before large quantities of goods start to be shipped over the summer for the Christmas shopping season.

Chinese imports rose at a slower 21.8 percent, to $144.26 billion, as government policies took effect to restrict bank lending in an attempt to control inflation. Japan accounts for about one-eighth of China’s imports, and these shipments barely increased from a year earlier, dragging down the overall total as the earthquake off northeast Japan triggered rolling electricity blackouts and parts shortages that disrupted the manufacture of cars and many other products.

Labor costs are surging by 10 to 30 percent a year in China and commodity costs are rising around the world, leading to warnings by suppliers of Western retailers that price tags will start rising globally. Many companies are searching for alternatives to manufacturing in China, but finding that nowhere else offers China’s combination of a large labor supply, world-class highways and ports and strongly pro-business policies, including a strict ban on independent labor unions that tended to hold down wages until very recently.

Josh Green, the chief executive of Panjiva, a New York company that advises 3,000 corporate buyers of goods from Asia, said his clients were extremely worried about the pace of price increases that they face from Chinese suppliers.

“That’s all I’ve been hearing from them over the past year, is concern verging on panic about the changing cost structure in China,” he said. “That has led to the hunt for the next China, which is a fool’s errand.”

Executives at three Chinese exporters said Tuesday that despite strong retail sales in the United States in April, they had not yet seen a sustained uptick in American orders, even as orders have risen from Europe and emerging markets. One reason might be that these and other exporters are now steadily marking up their prices to reflect the gradual appreciation of the renminbi, which has climbed 5 percent against the dollar since last summer.