British American Tobacco paid bribes to officials in east Africa, including two members of a convention created under the World Health Organization (WHO) to combat smoking, according to a BBC investigation airing on Monday.
The claims were immediately denied by the London-based tobacco giant and by the three officials named in the report, while the head of the convention's secretariat called for an investigation.
BBC's Panorama programme said its documentary was based on hundreds of confidential documents from a whistleblower—a former BAT employee who was based in Kenya and worked for the company for 13 years.
"BAT's bribing people. And I'm facilitating it. The reality is if, if they have to break the rules, they will break the rules," a statement quoted him saying.
But the company rejected the accusation in a statement, saying: "We have made it clear to the BBC that their sources are unreliable and that we categorically deny the suggestion that this is how BAT operates around the world."
"Any proven transgression results in disciplinary action and may lead to dismissal. We will not tolerate corruption in our business, no matter where it takes place," it said.
The documents used by the programme were said to reveal that BAT paid bribes of $3,000 (about 2,800 euros) each to two representatives of the WHO's Framework Convention on Tobacco Control (FCTC).
A third official who was formerly a representative to the FCTC allegedly received $20,000.
Vera Da Costa e Silva, head of the FCTC secretariat, said BAT had been "irresponsible", according to the BBC statement.
"It's using bribery at the cost of people's lives, simple as that. I think BAT should be investigated by the government and punished accordingly," she said.
British companies can be prosecuted for bribery in other parts of the world under the Bribery Act.