China has moved a rocket into position to launch a rover to Mars, in one of three forthcoming missions to the red planet, one from the US and another by the United Arab Emirates.

The Long March-5 carrier rocket is China's heaviest-lift launch vehicle and has been used experimentally three times, but never with a payload.

Dubbed Tianwen-1, China's first mission to Mars aims to land a rover to gather scientific data.

The rocket is due to blast off from the Wenchang Space Launch Centre in the southern island province of Hainan in late July or early August, according to state media reports on Friday that quoted the China National Space Administration.

The mission is one of the most ambitious yet for China's space programme, which has advanced rapidly since launching its first crewed mission in 2003.

Since then, it has sent astronauts to an experimental space station, begun work on a larger, more permanent facility and landed a probe on the less-explored far side of the moon.

This summer's trio of missions is the most sweeping effort yet to seek signs of ancient microscopic life, while scouting out Mars for future astronauts.

The timelines for such missions are daunting and the countries involved are striving to take best advantage of a one-month window in which Mars and Earth are in ideal alignment on the same side of the sun, minimising travel time and fuel use.

Such a window opens only once every 26 months.

Preparations have continued amid the coronavirus outbreak, which in part prompted Europe and Russia to drop their plans to send a life-seeking rover to Mars this summer.

Each spacecraft will travel more than 300 million miles before reaching Mars next February.

In the process, they will loop out beyond Earth's orbit and sync up with Mars' more distant orbit around the sun.

The US is sending a car-sized six-wheeled rover named Perseverance to collect rock samples to be returned to Earth for analysis in about a decade. Its launch date has been set for between July 30 and August 15.

The UAE spacecraft, named Amal, or "Hope" in Arabic, is an orbiter built in partnership with the University of Colorado Boulder and is now scheduled to launch from Japan on Monday. It will be the Arab world's first interplanetary mission.

Scientists want to know what Mars was like billions of years ago, when it had water sources that may have supported tiny life forms before turning into the frozen world it is today.

So far, the US has been the only country to successfully put a spacecraft on Mars, doing it eight times.

Two Nasa landers are operating there, InSight and Curiosity. Six other spacecraft are exploring the planet from orbit - three US, two European and one from India.

China's last attempt at a Mars mission in collaboration with Russia ended in failure in 2011. The Chinese space programme's close military connections and the relative secrecy within which it operates has limited its opportunities for co-operation with those of the US and other countries.

Meanwhile, China's foreign ministry has said it is not seeking to confront or replace the US as the world's top technological power but will fight back against "malicious slander" and attacks from Washington.

Hua Chunying responded on Friday to a series of recent accusations from the Trump administration.

She said China's chief concern is improving the livelihoods of its citizens and maintaining global peace and stability, despite what critics say is an increasingly aggressive foreign policy.

"As an independent sovereign state, China has the right to safeguard its own sovereignty, security and development interests, to defend the achievements made by the Chinese people with hard work, to refuse any bullying and injustice against China and to fight back against malicious slander and attacks by the US against China," Ms Hua told reporters at a daily briefing.

Her comments came in response to a speech on Thursday by US Attorney General William Barr in which he cautioned American business leaders against promoting policies favourable to Beijing.

He said at the beginning of the coronavirus pandemic China not only dominated the market on protective equipment, exposing American dependence on Beijing, but also hoarded supplies and blocked producers from exporting them to countries in need.

Mr Barr also accused hackers linked to the Chinese Government of targeting American universities and businesses to steal research related to coronavirus vaccine development.
He levelled the allegation against Beijing hours after Western agencies made similar claims against Russia.

Numerous allies of US President Donald Trump have issued strongly worded messages over China in recent days, coming at a time when bilateral relations have fallen to their lowest point in decades over issues from accusations of technology theft to China's claims in the South China Sea.

Ms Hua dismissed Barr's accusations of cyber theft related to vaccine development as "absurd".

"Because everyone knows that China is in a leading position in the research and development of new coronavirus vaccines, we have first-class scientific research personnel, and we do not need to gain a leading position with theft," she said.

Chinese companies have moved swiftly to develop a coronavirus vaccine as countries compete for the prestige and profits that would come with being the first to bring such a product to market.