To be sure, the details of commitment are not clear. The state-controlled energy firm has promised the Canadian government an annual compliance report on all its commitments that are part of its takeover of Nexen Inc, China's biggest ever takeover. These include listing shares on Toronto stock exchange, which comes with certain disclosure requirements.

But when capital is king, cash-rich Chinese state-owned enterprises have the balance of power in any acquisition talks, leaving doubts about the real potency of transparency pledges.

"On the transparency side, I believe there will be efforts from foreign governments to get more information, but it's still a question of how far China is willing to give," said Robert Lewis, a partner at Zhong Lun law firm in Beijing.

"Twenty years ago it was all about foreign capital coming into China and that foreign capital having the leverage in negotiations. Now it's the other way round, so China will not have to give as much on the transparency side as some might suspect".

The international community has demanded greater transparency from China on a number of fronts for years, wary of its intentions as the country grew to become the second-biggest economy in the world and symbolic of a shift in global power to emerging nations.

On the latest front, U.S. securities regulators are in an intense stand-off with their Chinese counterparts over access to Chinese audit documents. Separately, a U.S. congressional advisory panel described Chinese investment in the United States as a "potential Trojan horse."

China's state-secrets laws, massive bureaucracy and cronyism make it difficult to get key, verifiable information from Chinese companies.

FINANCIAL CLOUT

But the same Chinese companies yield considerable global clout. Chinese companies launched $51.3 billion of overseas acquisitions this year, second only to Japan, Thomson Reuters data shows, making the country one of the world's most active buyers of corporate stakes and businesses abroad.

Much of that acquisition power is led by China's government-run companies, and its energy sector, which has both the cash and the need to build up oil-and-gas supplies to fuel the $5.8 trillion economy.

The government owns all large financial institutions, which lends according to state priorities and directives and which favour large state enterprises -- one reason why the Washington think tank, the Heritage Foundation, ranks China 138th out of 179 in global economic freedom.

Even Chinese companies that aren't classed as state-owned enterprises, such as telecom giants Huawei and ZTE, face accusations they could covertly gather information for Beijing.

In October, a U.S. congressional report urged American companies to stop doing business with the two companies saying the Chinese government could take advantage of their equipment for espionage purposes. Canada and Australia have also indicated they will ban Huawei from taking part in communication network projects due to cyber security concerns.

The Nexen deal, and a separate though less contentious $5.3 billion offer by Malaysia's Petronas for Canada's Progress Energy, provided capital infusions to two Canadian companies, not to mention payouts to shareholders at a time of economic uncertainty.

Such considerations may trump the fear of a state-owned bogeyman coming to town.

"No government in the world is going to say 'we don't want your money'," said Andrew Lumsden, a partner at Corrs Chambers Westgarth in Sydney. "There will be a bit of huffing and puffing but it's probably business as usual".

GROUND RULES

Last week, the U.S. Securities and Exchange Commission (SEC) charged the Chinese affiliates of five of the world's biggest audit firms with violating U.S. securities law.

The United States and China could still reach a settlement, but the action shows the U.S. securities watchdog and their Chinese counterparts could not find agreement on the exact topic under discussion with CNOOC-Nexen: transparency of information.

Canada though is following in the steps of other countries that have attracted money from state-backed Chinese companies, such as Australia and Norway, in putting place a working set of ground rules.

"There's become an almost standard set of behavioral undertakings that firms accept in Australia from these kind of companies and reading between the lines it looks like the Canadians are doing similar," said Lumsden at Corrs Chambers Westgarth.

"The companies put in place a series of undertakings such as ensuring they have local management and comply with local environmental laws", he said.

Rupert Li, a partner at King & Wood Mallesons in Hong Kong, said all Chinese companies should study Nexen's transparency clause, particularly those that plan to venture abroad.

"If you want to be part of the global business community, people should have more visibility into your management, your finance, and who actually drives your strategy," Li said, adding the extent of a board's independence was also important.

"The question is whether the Chinese companies can actually dispel the notion that they are just part of the mandate from the Chinese government as opposed to being a true profit seeking entity," he added.

(Reporting by Rachel Armstrong and Michael Flahery: Editing by Neil Fullick)

• A Permanent Economic Emergency