(Releads with Canadian protest, adds details, background)
By David Ljunggren
OTTAWA, July 29 (Reuters) - Canada on Tuesday took the unusual step of singling out Chinese hackers for attacking a key computer network and lodged a protest with Beijing, raising tensions at a time when Ottawa wants to boost oil sales to China.
Officials said "a highly sophisticated Chinese state-sponsored actor" had recently broken into the National Research Council. The council, the government's leading research body, works with major firms such as aircraft and train maker Bombardier Inc..
Canada has reported hacking incidents before but this was the first time it had singled out China.
China is often cited as a suspect in various hacking attacks on companies in the United States and other nations. Beijing routinely dismisses such allegations.
Foreign Minister John Baird had "a full and frank exchange of views" about the case with Chinese Foreign Minister Wang Yi during a meeting in Beijing on Tuesday, said an official.
"The government takes this issue very seriously and we are addressing it at the highest levels in both Beijing and Ottawa," said Baird spokesman Adam Hodge.
Corinne Charette, Canada's chief government information officer, said that although NRC computers did not operate within the overall government system, they had been isolated as a precautionary measure.
"We have no evidence that data compromises have occurred on the broader government of Canada network," she said in a statement.
Separately, the NRC said it was working to set up a new secure network, which could take as long a year to build.
Canada's right-leaning Conservative government has had an uneven relationship with Beijing since taking power in 2006.
Citing human rights concerns, Prime Minister Stephen Harper initially kept his distance from China. Under pressure from business in Canada, he reached out gradually to Beijing.
Harper paid an official top-level visit in early 2012 and promised to do all he could to increase oil exports, citing the need to find new markets. The United States currently buys virtually all Canada's crude.
The attack on the NRC system was not the first hacking attempt in Canada that has been linked to China.
In September 2012, Canada said it was aware hackers had breached security at a domestic manufacturer of software used by big energy companies. Ottawa declined to comment on a report by a cyber security news site indicating a Chinese group was responsible.
The latest annual report from the Canadian Security Intelligence Service spy agency devotes a section to cyber security but does not mention China. Neither does Canada's official cyber security strategy.
Other nations have been less shy. The U.S. Department of Justice has charged a Chinese businessman with hacking into the computer systems of Boeing and other companies in order to obtain data about military projects.
This month, the New York Times reported that Chinese hackers in March broke into the computer networks of the U.S. government agency that keeps the personal information of all federal employees. (Reporting by David Ljunggren; Editing by Andrea Ricci)