China said on Friday that Taiwan remained the most important issue in its relations with the United States, days before President Hu Jintao heads to Washington.

Vice Foreign Minister Yang Jiechi also said differences on trade and economic policies, which are expected to dominate talks between Hu and President Bush, could be resolved and countered suggestions that China's rapid rise posed a threat to the rest of the world.

Yang Jiechi, vice foreign minister. [cnr]

But he reserved his strongest comments for Taiwan.

The United States recognizes the "one-China" policy, but it is also the biggest arms supplier to Taiwan and has pledged to defend the island of 23 million in case of attack.

"The Taiwan question is the most important, most sensitive core issue in the China-U.S. relationship," said Yang, who is also a former ambassador to Washington.

"We call on the United States to work together with China to oppose and counter secessionist activities on the part of Taiwan," he told a news conference.

He was speaking as Taiwan opposition politicians met Chinese leaders in Beijing and urged Taiwan to allow regular direct flights and expand trade.

Taiwan "president" Chen Shui-bian, who advocates independence, has alarmed the mainland with moves such as shelving guidelines on eventual reunification, which Beijing sees as a steps toward formal secession.

China will be seeking a clear show of support from Washington on Taiwan, analysts say.

"What the challenge is to both leaders is not how solid reassurances will be, it's how both can work together to try and manage the issue should Chen try to push the relationship," said Zhu Feng, an expert on China-U.S. relations at Peking University.

Yang called ties between Beijing and Washington "one of the most important bilateral relationships in the world" and said differences over a ballooning trade gap and the value of China's currency could be managed.

A trade delegation led by Vice Premier Wu Yi that has so far yielded deals worth more than $16 billion also proved "it is completely possible for China and the United States to properly handle trade friction," Yang said.

No business leaders will be accompany Hu, but Commerce Minister Bo Xilai and Ma Kai, head of the National Development and Reform Commission, will be among those in his delegation.

Yang said military personnel would also not be on the trip, despite concerns in Washington over double-digit increases in China's military spending.

Publishing policy papers on defense and invitations to foreign military observers showed China was committed to peaceful development, Yang said.