Once a gold mine for a select few foreign railway construction companies, China is now looking to compete with the global conglomerates that helped build its rail lines in the first place.

Chinese firms are already building high-speed rail links in Turkey and Venezuela, but the railways ministry has said it wants to export "Chinese technology" to North and South America as well as Europe.

In Saudi Arabia, the German giant Siemens is said to have forged an alliance with a Chinese consortium for a high-speed rail link between the holy cities of Medina and Mecca, after realising it could lose the tender to the consortium.

The move highlights the emergence of Chinese firms as major players on the railway scene, helped along by government financial support.

Foreign companies are not just competing with individual Chinese firms, they are coming up against a Chinese government eager to develop its rail sector and pouring money into state firms to do it, said Ren Xianfang, analyst at IHS Global Insight.

But "on a stand-alone basis, domestic firms in China are obviously still not in the same league as their overseas peers", Ren said.

The vastness of China's own rail ambition is another asset. The government plans 120,000 kilometres (74,400 miles) of track by 2020 -- up from 86,000 kilometres now -- and more than 40 percent of it would be high-speed links.

In December, China inaugurated the fastest high-speed railway in the world between Wuhan in the centre of the country and southern Guangzhou. Thanks to foreign technology transfers, its average speed is 350 kilometres an hour.

"In a few years, half of the world's high-speed mileage will be in China," said Frederic Campagnac, founder of consulting firm Clevy China, which specialises in the transport and construction sectors.

"They are also building the most rolling stock at the moment," a sector that is "not entirely automated and requires a qualified workforce. China is acquiring know-how fast," he said.

However, according to a source working for a European railway firm who asked not to be named, the Chinese "still need foreigners for high-speed railways".

In Chinese-foreign teams such as the alliance in Saudi Arabia, "one can imagine that China brings low-cost production for mechanical parts, and Siemens contributes high-technology and the high-end image", the source said.

"For the moment, we're in a classic pattern -- the Chinese copy what is easy to copy but can't manage to master the overall system."

Still, their presence is a growing challenge to traditional giants -- Canada's Bombardier Transportation, France's Alstom, and Siemens.

Together with the Japanese firm Kawasaki Heavy Industries, they have helped China build 6,550 kilometres of high-speed links thanks to technology transfer, but now find themselves largely on the sidelines of the Chinese market.

Last year, the head of Alstom Transport, Philippe Mellier, even called on Western countries to refuse to buy Chinese trains, denouncing the Asian nation's gradual shutting down to foreign suppliers.

Technology transfers normally come with clauses saying that the savoir-faire acquired by Beijing can only be used on Chinese territory, but the European railways firm source said the country has found a loophole.

"Their method is that they change five percent of the system, and then say they have redeveloped it," the source said.

"It is very hard to judge whether the corporate strategy of 'technology for market' is a wise decision at this moment," added Ren.

"While foreign companies have virtually created competitors of their own through technology transfer, they should have also gained handsomely from their entry into the China market."