According to the Ministry of Commerce, the first half trade surplus jumped 54.9 percent to 61.45 billion dollars, a result likely to lead to even more calls by China's trading partners for a faster and more radical appreciation of the yuan, they said.

"Perhaps the tightening measures are starting to have some effect by cooling China's demand for foreign goods," Lehman Brothers economist Rob Subbaraman said.

"Import growth is looking weaker than what we thought and that is a big difference."

Imports in June grew 18.9 percent year-on-year to 66.81 billion dollars but exports expanded faster, up 23.3 percent to 81.31 billion dollars.

Similarly for the first half, imports were up 21.3 percent to 367.15 billion dollars while exports increased 25.2 percent to 428.59 billion dollars.

"The trade surplus is continuing to expand," said Qu Hongbin, an economist at the Hong Kong and Shanghai Banking Corp. "If anything the monetary tightening will slow investment, this will slow imports, and so we should expect a big surplus."

Other data Monday supported the view that efforts to slow an economy that grew 10.3 percent in the three months to March are beginning to have an effect.

Money supply growth, a key measure of economic activity, slowed in June, with the M2 measure, or cash in circulation and all deposits, up 18.4 percent compared with a year earlier, the China Securities Journal reported.

In contrast, M2 rose 19.1 percent in May, according to previous reports.