The BBC investigation alleged that Aliou Sall received a secret payment of $250,000 in 2014 from Frank Timis, a businessman whose company, Timis Corporation, that year secured licences to two major offshore gas blocks. That was despite the lack of finances and experience that such an operation requires.

The affair has dominated the airwaves in Senegal, overshadowing the beginning of Sall’s second term, which he fought on an anti-corruption ticket. Protesters have taken to the streets of the capital Dakar in recent weeks and the country’s top prosecutor has launched an investigation, Reuters reported. 

Aliou Sall, who is mayor of a Dakar suburb, said June 24 he was resigning from his position in a body linked to the national treasury, but denied that he received a payment from Timis. In a statement he said the allegations were part of a campaign to “dehumanise” him and make him “public enemy number one,” its report continued.

London-based BP in 2017 agreed to pay Timis Corp $250mn for a stake in the licences, plus about $10bn in royalty payments over the coming decades, the BBC said. BP said before the programme aired that it did full due diligence before paying any money. Both Timis and BP deny any wrongdoing.

"These allegations are entirely false,” said a statement in response from Frank Timis and Timis Corporation. “There has been no wrongdoing whatsoever in relation to the Saint-Louis Offshore Profond and Caya Offshore Profond oil and gas concessions.”

The energy major told the BBC that its investments will bring “substantial benefits” to Senegal and insisted that the royalty payments are not even close to $10bn. It added that it had carried out ample due diligence before signing the deal.

The BBC says documents show BP was aware of Timis Corporation's payments to the president's brother, and went ahead with the deal anyway.