New revelations have emerged that China used cyberattacks to access data from nearly 40 US Pentagon weapons programmes and the blueprints for Australia's new spy headquarters.

Almost 30 other defense technologies have increased pressure on US leaders to take more strident action against Beijing to stem the persistent breaches.

The disclosure was included in a Defense Science Board report released earlier this year.

It is only now being discussed publicly after Defense Secretary Chuck Hagel heads to Southeast Asia.

He will discuss the escalating cyberthreat with counterparts from area nations.

Officials have been warning for years about China's cyber espionage efforts aimed at US military and high-tech programmes.

The breadth of the list underscored how routine the attacks have become.

It heightens worries that China can use the information to blunt America's military superiority.