According to a Reuters report on the issue, the upgrade follows a strengthening of British American Tobacco's credit metrics since leverage peaked in 2008.
In addition, the gradual reduction of litigation risk, as well as scope for maintaining a conservative capital structure, have also helped.
BAT's Long-term foreign currency Issuer Default Rating (IDR) and senior unsecured ratings were upgraded to 'A-' from 'BBB+'.
The Short-term IDR has been affirmed at 'F2'.
The Outlook is Stable.
Elsewhere on the markets: fuel prices fall
Three supermarket chains have cut their petrol prices again, reducing the cost of fuel by 2p at pumps across the nation.
Asda was the first to announce the discount, which follows similar reductions towards the end of last month.
It will now charge 137.7p for a litre of diesel and 131.7p for unleaded petrol on its forecourts.
Sainsbury's and Tesco followed suit, saying they would also slash 2p off their prices.
Get your bargain's at Comet
Meanwhile, electronics retailer Comet has announced a "massive stock liquidation" ahead of store closures as early as next week.
The sale, which began at 9am on Thursday, is only available in its 236 stores, with customers unable to buy products online.
The electrical chain said gift vouchers will be accepted on sale items, following the temporary suspension of the tokens over the weekend.
But it warned customers it will not offer refunds, and any items ordered before the company went into administration that have not been paid for will not be delivered