A leaked report written by MI5, the U.K.'s counter-espionage and security agency, warns that Chinese agents are eavesdropping on and stealing information from U.K. businesses, and trying to obtain trade secrets through blackmail.

The contents of the 14-page restricted report, authored by MI5's Center for the Protection of National Infrastructure, were revealed over the weekend in The Sunday Times.

The report charges China with conducting a concerted attack on U.K. critical infrastructure and with targeting the computer networks of public relations companies and international law firms. It also cautions U.K. business travelers about the security risks they face when visiting China.

"Hotel rooms in major Chinese cities, such as Beijing and Shanghai, which are frequented by foreigners, are likely to be bugged," the report warns, according to The Sunday Times.

The report says that undercover intelligence officers from the People's Liberation Army and China's Ministry of Public Security have approached U.K. business people with gifts of infected electronics and "lavish hospitality."

Such warnings are not new. In 2008, the U.S. State Department's Bureau of Consular Affairs issued an advisory to U.S. travelers headed to China for the 2008 Olympic Games. "All visitors should be aware that they have no reasonable expectation of privacy in public or private locations," the advisory warned. "All hotel rooms and offices are considered to be subject to on-site or remote technical monitoring at all times. Hotel rooms, residences, and offices may be accessed at any time without the occupant's consent or knowledge."

In a document titled "Foreign Travel Threat Assessment: Electronic Communications Vulnerabilities," published June 10, 2008, by the U.S. Department of Homeland Security's critical infrastructure threat analysis division , the DHS urged business leaders and U.S. officials to "leave [electronic devices] at home" when traveling because "[f]oreign governments routinely target the computers and other electronic devices and media carried by U.S. corporate and government personnel traveling abroad to gather economic, military, and political information."

Last week, McAfee, in conjunction with the Center for Strategic and International Studies (CSIS), published a cyber security report that found businesses face persistent attacks on their networks from cybercriminals and foreign governments. Last month, Google revealed that it and some 33 other companies had been targeted in just such an attack from China.

The U.S. State Department has asked China for an explanation of the attack on Google and other companies. China has responded by denying any involvement and stating that it's the biggest victim of cyber attacks.

The Dark Visitor, a Web site that reports on the activities of Chinese hackers, has compiled a selection of similar-sounding Chinese government responses to charges of involvement in cyber attacks, dating back to 2004.