BEIJING, March 30 (Xinhua) -- The United States' controls on exports to China have exacerbated the bilateral trade imbalance, and yuan appreciation will not solve the problem, China's Commerce Minister Chen Deming said Tuesday.

Chen was commenting on the yuan exchange rate issue for the second time since U.S. lawmakers called on the Obama administration to step up pressure on China to let yuan strengthen.

"It has been proved both in theory and practice that the appreciation of a nation's currency provides little help for improving balance of payments," Chen said in a bylined article posted on the ministry website.

Last week, Chen said at a forum that the yuan was not undervalued, and pressure for appreciation was "irrational" and would bring no good to either side.

The United States had practiced export controls against China for many years, forcing many Chinese purchasers away from the U.S., which exacerbated the trade imbalance, Chen said.