China's military says its soldiers have grown taller and wider over the past two decades, leading to cramped tanks and other equipment problems.

A survey of 20,000 troops begun in 2009 found they were an average of two centimetres (about three-quarters of an inch) taller and five centimetres (about two inches) bigger around the waist, the official People's Liberation Army Daily newspaper reported.

The added heft is causing discomfort for soldiers as they try to squeeze into tanks designed 30 years ago. It said rifle barrels were also becoming relatively shorter for the taller soldiers, leading to accuracy problems.

Adjustments would be made, with 28 body measurements taken into consideration when designing new firearms and other equipment, the report said.

China has the world's second-largest defence budget after the United States, spending heavily on new planes, ships, tanks and weapons of all sorts. Its 2.3 million-member standing army is the world's largest.