An intelligence report claims China is stepping up efforts to hack into U.S.-based commercial interests, raising new fears about trade secret theft.

The Washington Post reported Sunday that the U.S. continues to be a big target for cyber-espionage, with experts fearing theft of trade secrets and a threat to the nation's economic competitiveness.

China has been named as the country leading what's referred to as a "massive, sustained cyber-espionage campaign" against the U.S., despite continued denials from the government in Beijing.

According to sources familiar with classified documents from the National Intelligence Estimate, Chinese hackers have been increasing attacks against key sectors ranging from energy, finance and information to aerospace and automotive.

Few options

No longer a concern only for U.S. military and intelligence officials, the increasingly sophisticated attacks also include enlisting Chinese citizens already in the country with access to corporate networks, where theft is carried out via email and USB thumb drives.

Other targets include newspapers such as The New York Times, The Wall Street Journal and The Washington Post as well as search giant Google, which announced a major intrusion by Chinese hackers nearly two years ago.

Even as the Obama White House attempts to find solutions for preventing trade secret theft online, the report noted that companies are ultimately responsible for how each handles such incidents.

In addition to building evidence of seemingly invisible attacks against them, corporations risk burning bridges - not to mention economic interests - with countries like China and others accused of such activity.

Some readers will remember that a reported Twitter hack last week potentially impacted high profile users, including President Obama. There's been no connection made between China and that hack (at least not publicly), but the situation, said to have impacted some 250,000 users, is still unsettling.