The US is the target of a massive cyber-espionage campaign, mostly backed by China, threatening the country's economic competitiveness, a new intelligence report has said.

The National Intelligence Estimate identifies China as the country most aggressively seeking to penetrate the computer systems of American businesses and institutions to gain access to data that could be used for economic gain, the Washington Post reported.

The classified report, which represents the consensus view of the US intelligence community, describes a wide range of sectors that have been the focus of hacking over the past five years, including energy, finance, information technology, aerospace and automotives, the paper said, citing individuals familiar with the report.

The assessment does not quantify the financial impact of the espionage, but outside experts have estimated it in the tens of billions of dollars.

Cyber-espionage, which was once viewed as a concern mainly by US intelligence and the military, is increasingly seen as a direct threat to the nation's economic interests.
In a sign of such concerns, the Obama administration is seeking ways to counter the online theft of trade secrets, according to officials.

Analysts have said that the administration's options include formal protests, the expulsion of diplomatic personnel, the imposition of travel and visa restrictions, and complaints to the World Trade Organisation.

Cyber-espionage is "just so widespread that it's known to be a national issue at this point," said one administration official, who like other current and former officials spoke on the condition of anonymity.

The National Intelligence Estimate names three other countries, Russia, Israel and France, as having engaged in hacking for economic intelligence but makes clear that cyber-espionage by those countries pales in comparison with China's effort.

The New York Times, the Wall Street Journal and The Washington Post recently disclosed that they believe their networks were compromised in intrusions that originated in China.

China has staunchly rejected such allegations, saying the Beijing government neither condones nor carries out computer hacking.

Dating to at least the early 1980s, China has made the acquisition of Western technology, through means licit and illicit, a centerpiece of its economic development planning.

The explosion in computer use has greatly aided that transfer of technology.

China's intelligence services, as well as private companies, frequently seek to exploit Chinese citizens or people with family ties to China who can use their insider access to US corporate networks to steal trade secrets using thumb drives or e-mail, according to a report by the Office of the National Counterintelligence Executive.