China's military has set up 15 new units - covering everything from logistics to equipment development, political work and fighting corruption - as part of an on-going drive to modernise the world's largest armed forces, the Defense Ministry said.

President Xi Jinping's push to reform the military coincides with China becoming more assertive in its territorial disputes in the East and South China Seas. China's navy is investing in submarines and aircraft carriers and its air force is developing stealth fighters.

Late last year Xi inaugurated a general command unit for the army, a missile force and a strategic support force for People's Liberation Army (PLA), and the 15 new units follow on from that decision.

The Defence Ministry, in a statement released, said the new units would help the military function better and consolidate the Communist Party's control.

One of the 15 new departments is a dedicated auditing office, which will "organise and guide audits and supervision for the entire military" and strive to be independent, the ministry said, without giving details.

The PLA is reeling from Xi's anti-corruption campaign, which has seen dozens of officers investigated, including two former vice chairmen of the Central Military Commission, Guo Boxiong and Xu Caihou.

Some analysts say Xi, who heads the Central Military Commission that runs the armed forces, is also eliminating rivals.

Xi, in comments carried by state media, urged the armed forces to be "loyal, clean and responsible" and that they should learn "profound lessons" from Xu and Guo's cases.

Xu died of cancer last year before he could be put on trial. Guo has yet to face a court.

China has been moving rapidly to upgrade its military hardware, but integration of complex systems across a regionalised command structure has been a major challenge, something the reforms aim to address.

The armed forces are also losing 300,000 members, following a surprise announcement by Xi in September.

The troop cuts and broader reform programme have proven controversial, and the military's official newspaper has published a series of commentaries warning of opposition to the reforms and concern about job losses.

In a front page commentary, the People's Liberation Army Daily admitted that "everything is hard in the beginning", and urged the military to unite behind Xi.

"We must keep the mission and our responsibility firmly in mind," it said.