BEIJING - China and Russia are considering building a high-speed rail line stretching thousands of kilometres from Moscow to Beijing that would cut the journey time from six days on the celebrated Trans-Siberian to two, Chinese media reported.

The project would cost more than US$230 billion (S$293 billion) and be over 8,000km long, the Beijing Times reported - more than three times the world's longest high-speed line, from the Chinese capital to the southern city of Guangzhou.

The railway would be a powerful physical symbol of the ties that bind Moscow and Beijing: their political relationship has roots dating from the Soviet era and the two often vote together on the United Nations Security Council.

They have also strengthened their relationship as Western criticism of Russian President Vladimir Putin mounts over the Ukraine crisis and other issues.

The two countries signed a memorandum of understanding this week during Premier Li Keqiang's visit to Moscow, in which Beijing expressed interest in building a fast-rail link between the Russian capital and Kazan in the oil-rich Tatarstan region, state broadcaster China Central Television reported yesterday.

The 803km line would be the first stage of the route to Beijing, CCTV reported.

At present, trains between the two countries run along the Trans-Siberian railway that links Moscow and Vladivostok, before switching to a branch line heading south through the Mongolian capital Ulan Bator.

Direct passenger trains between Beijing and Moscow went into operation in 1954 and there are still two services per week, CCTV said. The new link would cut the train travel time from six days to under two days, the Beijing Times quoted Mr Wang Mengshu, a tunnel and railway expert at the Chinese Academy of Engineering, as saying.

"If the funds are raised smoothly... the line can be completed in five years at the quickest," he said.

The paper cited a research report that put the cost of one kilometre of Chinese-built fast rail at US$33 million.

China has the world's largest high-speed rail network, built from scratch in less than a decade, relying on technology transfer from foreign companies.

Its reputation was tarnished after a bullet train collision in July 2011 near the eastern city of Wenzhou that killed at least 40 people and injured hundreds.

But China is keen to promote the export of its technology, and has been building high-speed rail networks in Turkey and Venezuela.

AGENCE FRANCE-PRESSE