United Nations experts have unmasked a secret mission of private western forces in Libya, including Australian, British and US military operatives, according to a confidential report seen by the dpa news agency.

At least 20 people from Australia, France, Malta, South Africa, Britain and the United States were reportedly involved in the so-called “project Opus” mission in support of powerful Libyan General Khalifa Haftar.

According to the report, they boarded a cargo plane in Amman, Jordan, at the end of June 2019.

Officially, they were travelling on behalf of the scientific community to carry out “geophysical and hyperspectral investigations” in Libya on behalf of Jordan.

But the UN report calls this a “cover-up story”.

According to the information, they are members of privately owned military companies.

Private Australian forces were involved in a military operation in Libya. Photo: Getty

They were allegedly supposed to stop Turkish supply ships on their way to the coastal capital city of Tripoli, and intercept arms supplies meant for opposing forces, according to the report.

Oil-rich Libya has been in turmoil since a 2011 revolt toppled long-time dictator Muammar Gaddafi.

It has become a battleground for rival proxy forces.

A power struggle rages between the internationally recognised unity government in Tripoli and General Haftar.

Since last April, the eastern forces led by General Haftar have been trying to seize the capital Tripoli.

The UN has documented foreign mercenaries working in the country.

Libya’s UN-recognised Government of National Accord (GNA) forces attack the militias of renegade general Khalifa Haftar. Photo: Getty

It said the current arms embargo has also been violated many times, with weapons coming in from places including Turkey, which supports the unity government.

According to the report on the newly discovered mission, planning of the secret operation was mainly carried out by companies based in the United Arab Emirates – the report highlights “Lancaster6” and “Opus Capital Asset”.

They had reportedly procured six military helicopters in South Africa in mid-June 2019, first brought to Botswana by land and then flown to Benghazi in Libya, a Haftar stronghold.

At the same time, at the southern tip of Europe in Malta, “Opus Capital Asset” rented two military inflatable boats to be equipped with machine guns and taken to Benghazi on June 27.

The alleged secret mission was aborted for unknown reasons after only a few days.

There are no immediate indications that any attacks have actually been carried out.

The UAE is regarded as an important supporter of General Haftar in the civil war.