It established the Kunlun station there 10 years ago, setting up research facilities including a telescope array for astronomical observation and monitoring space debris.

But the US has since set up its own, temporary base about 100km (62 miles) away from Kunlun, which some Chinese researchers see as an attempt to block Beijing’s ASMA plan.

The US base appears to be backed by the US military programme supporting Antarctic activities, Operation Deep Freeze, according to a Chinese polar scientist who asked not to be named due to the political sensitivity of the issue.

The US Antarctic Programme declined to comment on the development.

China has stepped up its activities in Antarctica in recent years, building a permanent airfield, two permanent stations, Great Wall and Zhongshan, and two seasonal stations, Kunlun and Taishan. A fifth Chinese station is also being built.

Chinese scientists say the US has also expanded its presence in the region, raising concerns that competition between the two countries has now been extended to the South Pole.

Responding to a query about the US presence, the foreign ministry stressed that China was open to cooperating with other countries in Antarctica.

“The South Pole is crucial to the survival and sustainable future of the human race. [It] should become a new frontier of multinational cooperation, rather than an arena for power plays,” the ministry said.

“Building a peaceful and stable Antarctica which is environmentally friendly and with a fair governance system is in the interests of mankind,” it continued.

“China is willing to work together with other countries to turn Antarctica into a new high point of international cooperation and for the further development of the South Pole.”

Under the Antarctic Treaty System signed by 54 nations, the role of an ASMA is to “assist in the planning and coordination of activities within a specified area, avoid possible conflicts [and] improve cooperation”.

The country that proposes an ASMA usually has the biggest say on how it is managed.

But Beijing’s campaign, which has been going on for several years, has met with “fierce” opposition from the US, according to one scientist who was familiar with the negotiations.

“It is a battle of political will, military power, global influence … and it has been heating up noticeably in recent months,” said the government researcher who declined to be named because he is not authorised to speak to the media.

It was not clear when the US base was established but some Chinese researchers said it appeared to have been set up “overnight”, with equipment and personnel flown in by air.

Although it appears to be a makeshift facility, it is the only other presence in the area apart from the Chinese station and has been seen by Beijing as a prelude to further US activities.

Many satellites including spy and military probes use a polar orbit to achieve global coverage, and after service they become junk. The US has expressed interest in setting up a powerful laser in Antarctica to be used to fire at, and clean up, space debris.

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But strong air turbulence over American sites in the region – such as Dome Circe, or Dome C – could affect the aim of laser beams, among other problems.

Conditions at Dome Argus, however, are better than anywhere else on the continent – the average wind speed is just 2 metres per second, year round. Earlier this month, Chinese scientists said they had made a record astronomical sighting from the ice dome, claiming it was the best location for star gazing on Earth.

Claude Phipps, a space laser expert and founder of Photonic Associates in Santa Fe, New Mexico, said Dome Argus could be an ideal location to mount a big laser.

“Because so many debris are in a polar orbit, density increases at the poles, and this is a special advantage for a debris clearing or debris tracking site,” he said.

Tony Travouillon, an instrumentation scientist with the Australian National University in Canberra, agreed that the area had ideal conditions for laser experimentation but said it would require significant upgrades at the Kunlun station, which at present is only habitable in summer.

“Dome A currently doesn’t have a wintering base … Space debris cleaning requires larger telescopes and a complex adaptive optics system that would be hard to run without a crew during the winter,” Travouillon said.

“As for the weaponisation of such technology, it is important to remember that the Antarctic Treaty forbids military and commercial activities on the continent,” he said.