A spokesman for US-based Creditcards.com (http://www.creditcards.com) has confirmed that the e-commerce vendor and credit card processing company was the victim of an extortionist who hacked into its website and exposed thousands of credit card numbers.

Lauren Jean of Creditcards.com admitted the extortion attempt was perpetrated "some time ago" by a man who apparently had a grudge against the Los Angeles-based affiliate of Humboldt Bank in Eureka, California.

Jean confirmed that the man was angry with the company because it wouldn't give in to his demands for money. The man chose to take out his anger by hacking into the firm's website and exposing approximately 55,000 credit card numbers on the internet, Jean said.

He added that he didn't know if the numbers were still exposed and wouldn't comment on where the numbers were revealed.

"We have contacted our local FBI office, which is managing this case," Jean said.