China on Wednesday upgraded its diplomatic ties with Uzbekistan and offered closer cooperation across a range of projects, including a Central Asia railway that would open up a new trade route as shippers shun an existing overland link via Russia.

China-Central Asia Summit in Xi'an.

The two countries have elevated their ties to an "all-weather comprehensive strategic partnership" from a "comprehensive strategic partnership" previously, China's official news agency Xinhua reported, as Chinese President Xi Jinping met his Uzbek counterpart Shavkat Mirziyoyev in Beijing.

In an "all-weather" partnership, both sides maintain friendly relations at all times regardless of the international and domestic political landscape. China has a similar "all-weather" partnership with Belarus, another nation which Beijing views as strategic and has increasingly wrought closer ties.

China said it was ready to expand cooperation with Uzbekistan across the new energy vehicle industry chain, as well as in major projects such as photovoltaics, wind power and hydropower.

Notably, China called for work on the construction of the China-Kyrgyzstan-Uzbekistan railway to start "as soon as possible", after officially sealing closer ties with Uzbekistan.

The project has been discussed since the 1990s but gained new importance after the invasion of Ukraine prompted sanctions on Russia which resulted in shippers between China and Europe avoiding sending goods overland via Russia.

In the long term, the Central Asia route could potentially help cut freight transport times between China and Europe.

But financing and technical details for the China-Kyrgyzstan-Uzbekistan railway project remain unclear, as is its actual route across the three countries.

It is also unclear how goods would reach Europe from the western terminus of the proposed railway; potentially they could be transported via the Caspian Sea and the Caucasus or overland via the Middle East.