The brother of Senegal's president has resigned as head of a state-run savings fund after the BBC named him in a report over alleged corruption.
The report alleged that Aliou Sall was secretly paid $250,000 (£196,300) in 2014 by a gas company that sold its shares in Senegalese gas fields to BP.
Mr Sall has denied the claims, calling them part of a campaign to make him "public enemy number one".
Senegal's attorney general said an investigation had been launched.
"This unfortunate controversy is based only on untruths," Mr Sall said in a statement on Monday.
He had directed Senegal's Caisse des Depots et Consignations, or CDC fund, since September 2017.
In 2012, Senegal's then government awarded exploration rights for two offshore oil and gas fields to Petro-Tim. The firm was part of Timis Corporation, run by Romanian-Australian business tycoon Frank Timis.
The company had no previous experience of oil and gas exploration and an investigation - ordered by President Macky Sall after he took office - concluded that Petro-Tim should lose its concessions. President Sall still pushed the deal ahead, leading to protests in Senegal.
According to the BBC investigation, his brother was later hired by Timis Corporation and paid $1.5m (£1.18m) over five years. Aliou Sall was also promised shares in some of Mr Timis's companies which were worth $3m.
When gas was discovered in the two fields in 2016, BP agreed to pay between $9bn (£7.06bn) and $12bn in royalties to Timis Corporation for its stake, over a 40-year period.
The BBC investigation said documents showed BP was aware of Timis Corporation's $1.5m payments to the president's brother, and went ahead with the deal anyway.
Records also allegedly show that, in 2017, an offshore trust owned by Frank Timis secretly paid $250,000 (£196,000) to a company owned by Aliou Sall, which it said was for "tax due to the Senegalese government".
BP said it had conducted extensive due diligence and that figures published by the BBC were inaccurate. Mr Timis has also denied any wrongdoing.
There have been protests in Senegal's capital, Dakar, against the deal
President Sall has weighed in on the affair, calling the accusations an attempt to destabilise the country.
His brother had already stepped down in October 2016 from his post at Timis Corporation after facing criticism of a possible conflict of interest.
The report has dominated the country's media and prompted protests in the capital, Dakar. Political opponents and civil society groups have demanded "transparency" in contracts related to gas and oil exploration in Senegal.
One MP, Aymérou Gning, has told local media that a parliamentary inquiry could be opened.