The Chinese government has refused to allow a U.S. warship to make a routine port call in Hong Kong next month, in an apparent protest over recent U.S. dealings with Taiwan.

The destroyer, the USS Curtis Wilbur, had sought clearance to visit Hong Kong for several days in early April, but the Chinese government has refused to grant it permission.

US diplomats in Hong Kong confirmed that permission had been denied but refused to speculate as to why.

Chinese Foreign Ministry Spokeswoman Zhang Qiyue did not address the issue directly, but said decisions on port calls are based on various factors and are approved on a case-by-case basis.

She also suggested that Vice President Hu Jintao's planned visit to Washington next month will only go ahead if the United States plays by China's rules over the issue of Taiwan. Ms. Zhang said "The Taiwan issue is the most important and the most sensitive issue at the heart of U.S.-China relations. To secure a healthy and smooth development of bilateral ties the U.S. side should properly handle this question. We demand that the U.S. should meet its words with deeds and cease interfering in China's internal affairs by using Taiwan issues and undermining bilateral ties," Ms. Zhang said.

At issue is a U.S. decision to allow Taiwan's defense minister to attend a military conference in the U.S. state of Florida earlier this month. The Chinese protested strongly, calling in the U.S. ambassador to China to express displeasure.

Beijing views Taiwan as a renegade province and will not condone any move that appears to recognize the island as an independent country. The United States is Taiwan's biggest military supplier and has pledged its protection in the event of an attack by mainland China.

Last year China imposed a temporary ban on U.S. warships visiting Hong Kong after a collision between U.S. and Chinese military planes over the South China Sea.

Relations between the United States and China had been improving since September 11th when nations came together to cooperate in a global war against terrorism. President Bush has visited China twice since then.