The Serious Fraud Office (SFO) has opened an investigation into British American Tobacco, the FTSE 100-listed cigarette maker confirmed today.
Shares in BAT tumbled 3.7 per cent to 4,694.5p at the open.
"As previously announced, we are investigating, through external legal advisers, allegations of misconduct," BAT said in an announcement to the London Stock Exchange.
"We have been co-operating with the Serious Fraud Office and British American Tobacco has been informed that the SFO has now opened a formal investigation. BAT intends to co-operate with that investigation."
The SFO confirmed in a statement this morning that it is "investigating suspicions of corruption in the conduct of business by BAT, its subsidiaries and associated persons", and called on anyone with information relevant to this investigation to contact the SFO through its secure and confidential reporting channel.
Shares in BAT plunged dramatically in late trading last Friday, after the US Food and Drug Administration announced plans to cut nicotine in cigarettes. The British company's stock fell 11 per cent to 4,747p.
BAT also recently completed the acquisition of US rival Reynolds, with the newly combined firm believed to be the biggest tobacco group in the world.