The Democratic Republic of Congo is on track to suffer a shortfall of nearly four billion dollars from mining and oil contracts that it signed with controversial Israeli billionaire Dan Gertler, an anti-corruption group said on Wednesday.

The United States hit Gertler with sanctions in December 2017 over mining deals he struck with help from his friend, the DRC's then president Joseph Kabila.

The tycoon had deprived the DRC of tax revenues of $1.36 billion over a decade, according to a 2013 report by the Africa Progress Panel chaired by former UN chief Kofi Annan.

On Wednesday, a coalition of anti-graft campaigners called The Congo Is Not for Sale (CNPAV) said that its own analysis of public finances found "the DRC lost income of $1.95 billion between 2003 and 2021."

"If nothing is done to stop this haemorrhage, an additional $1.76 billion could escape state coffers between 2021 and 2039," the CNPAV said.

CNPAV spokesman Jean-Claude Mputu told a news conference that "no intermediary has ever cost the country as dearly" as Gertler.

"Nothing is being done and money is still leaving the country," he said.

The DRC is one of the world's main producers of valuable minerals such as copper, gold, cobalt and coltan.

A cobalt plant in Lubumbashi, southeastern DR Congo. The vast central African country is rich in minerals but most of its people are poor
A cobalt plant in Lubumbashi, southeastern DR Congo. The vast central African country is rich in minerals but most of its people are poor AFP / SAMIR TOUNSI

But the country of 84 million is one of the world's poorest and is wracked by political violence.

The government has proposed a budget of the equivalent of $6.9 billion for 2021.

Gertler's profits in the DRC came to light in 2016 with the publication of the so-called Panama Papers.

The massive loss in revenue to the DRC, according to the United States, comes from the underpricing of mining assets that were sold to offshore companies linked to him.

Gertler, 47, has denied any suggestion of underhand dealing.

Some of the US sanctions against him were reversed by former president Donald Trump during his last days in office but were reimposed in March.

Mputu threw down the gauntlet to Kabila's successor, Felix Tshisekedi, who took office in January 2019 on pledges to root out the DRC's entrenched corruption.

Tshisekedi "so far has not taken any step aimed at investigating Mr. Gertler's mining transactions," Mputu said.

The country "desperately needs this money to rebuild its economy and get its population out of poverty."