U.S. Defence Secretary Chuck Hagel expects to visit China's sole aircraft carrier when he arrives in the country on Monday, a U.S. official said, in an unprecedented opening by Beijing to a potent symbol of its military buildup.

The planned carrier visit, which will come at the start of Hagel's three-day trip to China, was quietly approved by Beijing at Washington's request and had not been previously announced, the official said, speaking on condition of anonymity.

The Liaoning, a Soviet-era ship bought from Ukraine in 1998 and re-fitted in a Chinese shipyard, has been seen as a sign of Beijing's ambition for greater global influence and a reminder of its growing military might.

Hagel will fly to China's port city of Qingdao after a trip to Japan, and then head to a Chinese naval base. While there, he will visit the Liaoning, the official said.

Reporters travelling with Hagel were not expected to accompany him on the vessel.

A visit to China's aircraft carrier would not only be a first for a U.S. defence secretary. The U.S. official believed Hagel would be the first official visitor from outside China to be allowed on board, although that could not be immediately confirmed.

Military build-up

The disclosure of the carrier visit came a day after Hagel said he would use his first trip to China as defence secretary to press Beijing to use its "great power" wisely and respect its neighbours, who have been put on edge by its increasingly muscular military.

"Coercion, intimidation is a very deadly thing that leads only to conflict," he said at a news conference on Sunday at Japan's defence ministry.

"All nations, all people deserve respect."

China is locked in bitter territorial disputes with some of its neighbours, especially Vietnam and the Philippines, over claims to parts of the potentially oil and gas-rich South China Sea. China has a separate dispute with Japan in the East China Sea over a group of uninhabited islets.

Hagel, in his talks in Japan over the weekend and last week at a gathering of Southeast Asian defence chiefs in Hawaii, has sought to reassure allies of the U.S. security commitment to the region and has promised frank discussions in China.

China, in turn, has repeatedly urged the U.S> not to take sides in any of these disputes, and has watched warily as Washington moves to strengthen its military alliances in the region, especially with Tokyo and Manila.