Beijing has ploughed billions of dollars into modernising its military in recent years, a trend that has unnerved some governments in East Asia even though China claims its aims are peaceful.

China has two carriers currently in operation -- the Liaoning and Shandong -- while the Fujian is undergoing sea trials.

The Soviet-built Liaoning is China's oldest aircraft carrier, commissioned in 2012. The Shandong entered service in 2019.

China's navy said on Friday that the cross-regional trials and training for the Fujian "is a normal part of the aircraft carrier's construction process".

It is "not directed at any specific target", Leng Guowei, a spokesman for the Chinese navy, said in a statement.

Analysts at Washington-based think tank CSIS have said the Fujian is expected to feature more advanced take-off systems, allowing the Chinese air force to deploy jets carrying larger payloads and more fuel.

China has stepped up a massive expansion of its naval forces in recent years as it seeks to expand its reach in the Pacific and challenge a US-led alliance.

Beijing said in June that its Liaoning and Shandong carrier formations conducted combat drills in the western Pacific Ocean, unsettling regional neighbours including Japan.

A Taiwanese security official also said that month that Beijing had deployed its two aircraft carrier groups around the island in May.

The Communist Party has refused to rule out using force to seize control of Taiwan, a democratic, self-ruled island that China insists is part of its territory.