The OFT claims manufacturers and retailers "variously engaged in one or more unlawful practices in relation to retail prices for some or all of a number of tobacco products in breach of the Competition Act".
According to the OFT: "Arrangements between each manufacturer and each retailer restricted the ability of each of these retailers to determine its selling prices independently, by linking the retail price of a manufacturer's brand to the retail price of a competing brand of another manufacturer."
OFT chief executive John Fingleton said: "If we find evidence of anti-competitive activity, we are prepared to use the appropriate powers to punish the companies involved and to deter other businesses from taking part in such behaviour."
In a statement, Imperial said it would review the statement of objections and submit its response.
"Imperial Tobacco takes compliance with competition law very seriously and rejects any suggestion that it has acted in any way contrary to the interests of consumers," it said.