BEIJING -- China's currency should stay on the slow appreciation track, an economist with the nation's top economic planning agency said Friday. The yuan has risen three times this week.

Chen Dongqi, vice president of the National Development and Reform Commission's macro-economics research institute, called for "stabilizing expectations about renminbi (another name for the yuan) appreciation by means of fine-tuning."

The yuan's official exchange rate picked up on Wednesday, rising by 123 basis points, followed by a 79-point jump and a smaller 12-point rise on the following two days. On Friday, it traded at 7.9736 per US dollar, the central bank has announced.

Rejecting repeated calls from the United States for accelerated appreciation of yuan, Chen said in an interview with Xinhua that an increase in value of 3 to 4 percent per year is appropriate.

U.S. manufacturers argue the yuan is undervalued by as much as 40 percent, making Chinese goods cheaper in the United States and American products more expensive in China and hurting the US job market.

In July last year, the government revalued the yuan by 2 percent against the U.S. dollar and abandoned its peg to the dollar in favor of a restricted float against a group of foreign currencies.

The yuan has since risen by 3.7 percent against the US dollar.

"Exchange rate reform has not created instability, because the overall economy was performing normally. Some economic problems do exist, but they are not that serious," Chen said.

"The Chinese economy might not function optimally if the yuan appreciates too fast, but a small rise in the currency is acceptable," he said, saying that a gradual appreciation in the yuan's value would allow exporters to increase their foreign earnings.

Speculators betting on a hefty appreciation would be undermined if the Chinese currency turns out to rise only step by step.

The yuan is only allowed to move in a 0.3 percent band against the greenback each day.