WASHINGTON - Designs for many of the nation's most sensitive advanced weapons systems have been compromised by Chinese hackers, according to a report prepared for the Pentagon and to officials from government and the defense industry.

Among more than two dozen major weapons systems whose designs were breached were programs critical to U.S. missile defenses and combat aircraft and ships, according to a previously undisclosed section of a confidential report prepared by the Defense Science Board for Pentagon leaders.

Experts warn that the electronic intrusions gave China access to advanced technology that could accelerate the development of its weapons systems and weaken the U.S. military advantage in a future conflict.

The Defense Science Board, a senior advisory group composed of government and civilian experts, did not accuse the Chinese of stealing the designs. But senior military and industry officials with knowledge of the breaches said the vast majority were part of a widening Chinese campaign of espionage against U.S. defense contractors and government agencies.

The significance and extent of the targets help explain why the Obama administration has escalated its warnings to the Chinese government to stop what Washington sees as rampant cybertheft.

In March, the advisory panel warned in the public version of its report that the Pentagon is unprepared to counter a full-scale cyber-conflict.

The list of compromised weapons designs is contained in a confidential version, and it was provided to the Washington Post.

Some of the weapons form the backbone of the Pentagon's regional missile defense for Asia, Europe and the Persian Gulf. The designs included those for the advanced Patriot missile system, known as PAC-3; an Army system for shooting down ballistic missiles, known as the Terminal High Altitude Area Defense, or THAAD; and the Navy's Aegis ballistic missile defense system.

Also identified in the report are vital combat aircraft and ships, including the F/A-18 fighter jet, the V-22 Osprey, the Black Hawk helicopter, and the Navy's new Littoral Combat Ship, which is designed to patrol waters close to shore.

Also on the list is the most expensive weapons system ever built - the F-35 Joint Strike Fighter, which is on track to cost about $1.4 trillion. The 2007 hack of that project was reported previously.

China, which is pursuing a long-term, comprehensive strategy to modernize its military, is investing in ways to overcome the U.S. military advantage - and cyber-espionage is seen as a key tool in that effort, the Pentagon noted this month in a report to Congress on China.

For the first time, the Pentagon specifically named the Chinese government and military as the culprit behind intrusions into government and other computer systems.

As the threat from Chinese cyber-espionage has grown, the administration has become more public with its concerns.

In a speech in March, Thomas Donilon, the national security adviser to President Obama, urged China to control its cyber-activity. In its public criticism, the administration has avoided identifying the specific targets of hacking.

A recent classified National Intelligence Estimate on economic cyber-espionage concluded that China was by far the most active country in stealing intellectual property from U.S. companies.

The Chinese government insists that it does not conduct cyber-espionage on U.S. agencies or companies, and government spokesmen often complain that Beijing is a victim of U.S. cyberattacks.

Obama is expected to raise the issue when he meets with Chinese President Xi Jinping next month in California.

The confidential list of compromised weapons system designs and technologies represents the clearest public look at what the Chinese are suspected of targeting.

When the list was read to independent defense experts, they said they were shocked at the extent of the cyber-espionage and the potential for compromising U.S. defenses.

"That's staggering," said Mark Stokes, executive director of the Project 2049 Institute, a think tank that focuses on Asia security issues. "These are all very critical weapons systems, critical to our national security. When I hear this in totality, it's breathtaking."