People have flooded the Internet message board FatWallet.com with complaints of unauthorized charges ranging from $10 to $18 from a company called Global Telecom, based in Moscow.
"Because they are such small amounts, a lot of people may not notice the charges," said Kim Sebring, who told CNET News.com that her card was charged. "These guys are going to get away with a lot of money."
No one on the message boards had heard of Global Telecom, much less bought anything from it.
The FBI is aware of the complaints and is looking into the matter.
"These unauthorized credit card charges could be related to the current investigation into the hacking at Creditcards.com," FBI spokeswoman Laura Bosley said.
A representative at Creditcards.com said Thursday that the company was unaware of the Global Telecom allegations and did not know if it was related to its problem.
Creditcards.com said a suspected hacker stole the 55,000 credit card numbers and attempted to extort money from the company. The FBI is investigating the allegations.