Zardon

PALO ALTO, Calif. (Reuters) - Yahoo Inc. said on Thursday that some of its customers had been tricked into giving their credit card numbers to an unaffiliated third party that had posed as Yahoo in a mass e-mail.

Yahoo, which has a billing relationship with more than one million customers who pay for such services as expanded e-mail and online matchmaking, sent out its own mass e-mail Thursday morning advising customers not to respond to the bogus request.

A company spokeswoman said less than 24 hours had transpired between the time the fraudulent e-mail went out and the time that Yahoo sent out the advisory.

She said some customers had fallen for the e-mail request and supplied credit card information, but the majority had not.

The source of the fraudulent e-mail was not known.

Yahoo used to provide all of its content and online services for free, but has increasingly been charging for some enhanced services as a way to reduce its dependence on Internet advertising.