US President Donald Trump has scrapped regulations to enable American oil companies legally bribe foreign governments and secure lucrative mining and drilling rights.

“It’s a big deal,” Trump said to reporters in the Oval Office as he signed the resolution on Tuesday, repealing the Cardin-Lugar regulations.

The regulations were meant to fight corruption and made it mandatory for oil companies to disclose payments made to foreign governments to secure mining and drilling deals.

The repeal was made using the Congressional Review Act (CRA), which allows an incoming president to overturn new federal regulations. It is the first time the CRA has been used to repeal a regulation in 16 years.

Late last year, Russia sold a 19.5% stake in its giant oil company Rosneft, but the full identities of those who bought it still remain unknown.

Exxon, then led by Tillerson, was under investigation by Nigeria’s economic and financial crimes commission over lucrative oil rights it secured in 2009.

In 2011, the US oil and gas industry spent nearly $ 150 million in lobbying the US Congress, according to priceofoil.org, which believes that big oil gets a 5800% return on the money it spends through campaign contribution and lobbying.

“Trump has given an astonishing gift to the American oil lobby. This makes a mockery of claims by US oil companies such as Exxon that greater transparency would damage companies’ competitiveness. If the European companies can do it, you have to ask – what are US companies trying to hide?” said Zorka Milin, senior legal adviser at the advocacy group Global Witness.

Eric LeCompte, executive director of the religious development organization Jubilee USA, said: “In the short term, we lost a tool that can help track the billions of dollars lost to corruption and tax evasion in the developing world. Now we need to be sure that the new rule that the Securities and Exchange Commission writes will be a rule that can still stop corruption.”

Jubilee USA, which represents over 650 faith groups, fought for the passage of the Cardin-Luger rules in 2010 as a way of tackling bribery and corruption in developing countries that it argues exacerbate conflict and poverty. “Improving financial transparency and ending global poverty are two sides of the same coin,” said LeCompte.