A senior US defense official on Wednesday voiced doubts about China's insistence that its use of space is for peaceful means as Washington appealed for steady military ties with the rising Asian power.

"The Chinese have stated that they oppose the militarization of space. Their actions seem to indicate the contrary intention," said Wallace Gregson, the assistant secretary of defense in charge of Asia.

"We continue to press the Chinese for explanation," Gregson told a congressional hearing.

China says its rapidly growing military budget is for defensive purposes. Chinese President Hu Jintao pledged with US President Barack Obama at a November summit to promote the peaceful use of space.

However, China's air force commander told state media last year that militarization of space was a "historical inevitability."

China in 2007 became the third nation after the United States and the former Soviet Union to conduct a "Star Wars" test shooting down one of its own satellites.

On Tuesday, China said it had successfully intercepted a missile in a test of an air defense system in what analysts described as a show of strength after the United States finalized a sale of missile equipment to Beijing's rival Taiwan.

Admiral Robert F. Willard, the head of the US Pacific Command covering Asia, appealed to China not to sever military relationship after any future US arms package to Taiwan, as Beijing has done in the past.

Willard said he and Defense Secretary Robert Gates told a senior Chinese general, Xu Caihou, during his visit to the United States last year of the "mutual benefit of maintaining it regardless of differences."

"I think we will be testing the maturity of that military-to-military relationship in the future, not just over our legal obligations to conduct Taiwan arms sales but over other issues," Willard told the hearing.

China considers Taiwan, where the mainland's nationalists set up a rival government in 1949 after losing the civil war, to be a province awaiting reunification -- by force if necessary.

The United States in 1979 switched recognition to Beijing but the Congress approved the Taiwan Relations Act, which requires the US administration to provide arms to Taiwan to ensure its defense.