Beijing's first aircraft carrier has returned from a training mission in the South China Sea, state media said, completing a 37-day deployment carried out amid mounting regional tensions.

The newly-commissioned Liaoning returned to its home port of Qingdao after carrying out a series of trials with "aircraft, naval vessels and submarines", China's official news agency Xinhua reported on Wednesday.

"China's first aircraft carrier successfully completed 37 days testing and training in the South China Sea," said the report, which the defence ministry posted on its website.

The mission was carried out at a time of heightened tensions between China and its neighbours over territorial disputes.

Beijing declared air defence rights over much of the East China Sea in November, provoking a furious international reaction.

China also claims almost the whole of the South China Sea, even areas close to the coasts of other littoral states.

During the training mission Washington issued a formal protest after military officials said a US warship was forced to manoeuvre to avoid a collision with a Chinese naval vessel -- reportedly part of the group escorting the Liaoning -- that had "posed a threat" in the South China Sea.

The Liaoning is a refurbished vessel purchased from Ukraine. It went into service in September 2012, and top naval commanders have promised the country will have more aircraft carriers.