China reiterated its commitment to a more flexible yuan and stronger enforcement of intellectual property rights during President Hu Jintao's visit to Washington, a top Treasury official said on Friday.

Lael Brainard, the Treasury's Undersecretary for International Affairs, said the United States was pleased with the progress made during Hu's visit but added: We are not complacent.

China affirmed its commitment to enhance exchange rate flexibility and dropped previous references to maintaining basic stability at an equilibrium rate, Brainard told the Council on Foreign Relations.

Many economists and politicians in the United States argue that China has gained an unfair competitive advantage in international trade by artificially holding down the value of its currency, the renminbi, thereby making its exports cheaper.

Brainard praised China for the currency's appreciation of about 3.5 percent over the last six months, but said more was needed.

We will stay closely and intensively engaged with China as it navigates a course toward an increasingly market-determined and international currency, Brainard said.

She lauded China's assurances that it would do more to enforce intellectual property rights, saying the country had agreed to implement mechanisms for ensuring government agencies did not use pirated software.