China’s insatiable demand for energy is prompting fears of financial and diplomatic collisions around the globe as it seeks reliable supplies of oil from as far away as Brazil and Sudan.

An intrusion into Japanese territorial waters by a Chinese nuclear submarine last week and a trade deal with Brazil are the latest apparently unconnected consequences of China’s soaring economic growth.

The connection, however, lies in an order issued last year by President Hu Jintao to seek secure oil supplies abroad – preferably ones which could not be stopped by America in case of conflict over Taiwan.

The submarine incident was put down to a “technical error” by the Chinese government, which apologised to Japan.

But even before the incident the People’s Daily, the government mouthpiece, had commented that competition over the East China Sea between the two countries was “only a prelude of the game between China and Japan in the arena of international energy”.

The Brazil trade deal included funding for a joint oil-drilling and pipeline programme at a cost that experts said would add up to three times the cost of simply buying oil on the market.

The West, however, has paid little attention to these developments. For the United States and Europe are far more concerned with the even more sensitive issues of China’s relations with “pariah states”.

In September, China threatened to veto any move to impose sanctions on Sudan over the atrocities in Darfur. It has invested $3 billion in the African country’s oil industry, which supplies it with seven per cent of its needs.

Then, this month, it said that it opposed moves to refer Iran’s nuclear stand-off with the International Atomic Energy Agency to the United Nations Security Council.

A week before, China’s second biggest state oil firm had signed a $70 billion deal for oilfield and natural gas development with Iran, which already supplies 13 per cent of China’s needs.

China has its own reserves of oil and natural gas and once was a net oil exporter. But as its economy has expanded by an average of nine per cent per year for the last two decades, so has its demand for energy.

This year it overtook Japan as the world’s second largest consumer of energy, behind the US.

Its projected demand, boosted by a huge rise in car ownership as well as the need to find alternatives to polluting coal for electricity generation, has contributed to the surge in the price of oil this year. Shortages are already leading to power cuts in the big cities.

Since President Hu ordered state-owned oil firms to “go abroad” to ensure supply, they have begun drilling for gas in the East China Sea, just west of the line that Japan regards as its border.

Japan protested, to no avail, that the project should be a joint one.

The two are also set to clash over Russia’s oil wealth. China is furious that Japan has outbid it in their battle to determine the route of the pipeline that Russia intends to build to the Far East.

Japan favoured a route to the sea, enabling oil to be shipped to both Japan and China. China wanted an overland route through its own territory, which would give it ultimate control if hostilities broke out.

Increasingly, analysts are saying that China’s efforts have gone beyond what is safe or even in its own interests.

Claude Mandil, the executive director of the International Energy Agency in Paris, said the reserves in the East China Sea were hardly worth the trouble.

“Nobody thinks that there will be a lot of oil and gas in this part of the world,” he said.

“It may be a difficult political issue but I don’t think the energy content is worthwhile.”

Eurasia Group, a New York-based firm of political analysts, said its oil experts worked out that China was paying such an inflated price for its investment in Brazil that the cost for the oil it ended up with was three times the market price.

“If China’s economy falters, which, in my view, appears increasingly likely, then commodity prices will plummet, and with them, the value of the assets that produce them,” Jason Kindopp, Eurasia’s lead China analyst, said.

“Beijing may end up in a early 1990s Japan situation, where it is forced to sell recently purchased overseas assets for a fraction of what it paid for them.”

China’s wider aggression to secure oil and gas was the greatest threat to its international standing in the next decade.

“Sudan is the primary example,” he said.

“It marks the first time in recent years that China has promised to wield its veto power in the UN Security Council against a petition initiated by the United States and backed by France and Great Britain.”