China is preparing to launch a rocket carrying supplies for its new space station just days after landing a rover on Mars, as it hustles ahead with its extraterrestrial ambitions.

Beijing has pumped billions into its space programme in a bid to make up ground on pioneers Russia and the United States, with ambitious projects in Earth orbit and the landing of uncrewed craft on the Moon and Mars.

But it was heavily reprimanded by the United States and many experts for a potentially dangerous breach of space etiquette for letting a massive rocket segment free-fall to Earth earlier this month after launching the core module of China's space station.

In the upcoming mission, the Tianzhou-2 cargo craft will blast off on a 14-tonne Long March 7 rocket, and is expected to carry essentials such as food and space suits to the core module.

The space station -- named Tiangong, meaning "heavenly palace" -- will need around 10 missions in total to complete assembly in orbit.

Officials have not given an exact time for the latest mission, but say it will be launched from the southern island of Hainan.

China's maritime authorities have issued a navigation alert mentioning a "rocket launching" between 1700 GMT and 1800 GMT on Wednesday (between 1 am and 2 am in China), according to the Japanese Coast Guard website.

Hao Chun, director of the China Manned Space Engineering Office, said the construction of the space station has entered a "critical stage".

It is expected to remain in low Earth orbit for up to 15 years.

With the possible retirement of the International Space Station after 2028, China's could become the only human outpost in Earth orbit.

Although Chinese authorities have said they are open to foreign collaboration on their space station, the scope of that cooperation is as yet unclear.

But the European Space Agency has already sent astronauts to China to train for work inside Tiangong when it is ready.

The latest cargo launch will come just days after China landed its Zhurong rover on Mars, becoming only the third nation to successfully land a craft on the red planet.

The rover is expected to soon start studying Martian geology, spending around three months taking photos and harvesting data from a vast northern lava plain.