A Coca-Cola employee has been charged with stealing confidential information and trying to pass it to arch-rival PepsiCo.

Prosecutors in the US have charged three people - the employee and two friends - with fraud along with stealing and selling trade secrets, which included a sample of a new drink.

Coke learned of the theft and the attempted sale of the "very detailed and confidential information" from Pepsi, which was approached in May by an individual claiming to be a high-level Coke employee.

Pepsi received a letter from the individual, who called himself "Dirk", and passed it on to Coke, which immediately contacted the FBI.

"We just did what any responsible company would do," a PepsiCo spokesman told just-drinks today (6 July). "Competition has always been fierce but it must also be legal and fair."

Coke chairman and chief executive Neville Isdell expressed his "sincere appreciation" to PepsiCo for alerting the company to this "attack".

"While this breach of trust is difficult for all of us to accept, it underscores the responsibility we each have to be vigilant in protecting our trade secrets," Isdell said in a memo to employees.

A Coke spokesperson confirmed to just-drinks that the closely-guarded secret formula for flagship brand Coca-Cola Classic was safe. "The secret formula was never in jeopardy," she said.

According to prosecutors, the trio - Joya Williams, an executive administrative assistant at Coke, Edmund Duhaney of Decatur, Georgia and Ibrahim Dimson, or 'Dirk', of Bronx, New York - tried to sell the information in deals worth US$1.5m.

During the FBI investigation, video surveillance showed that Williams was the source of the information. Prosecutors said that she was caught on video looking for company files and stuffing them into bags. Prosecutors added that the video also showed Williams holding a liquid container with a white label, which resembled the description of a new Coke product sample before placing it into her bag.

Coke later checked the sample was genuine and said it was in fact a product being developed by the company.

Prosecutors said that during the investigation, Dimson provided an undercover agent with 14 pages of Coke documents the company later identified as valid and highly confidential, prosecutors said.

Dimson asked for US$10,000 for the documents and later agreed to be paid US$75,000 for the purchase of a highly confidential new product sample, prosecutors said.

The trio were arrested yesterday, when the US$1.5m deal to sell other trade secrets was scheduled to take place, prosecutors added.