The Viacom Inc. network told about 5,000 employees in an e-mail that their names, Social Security numbers and dates of birth had been stolen, The Wall Street Journal reported. Some employees also reportedly had information regarding their salaries stolen.

"We are taking every appropriate action to investigate this incident and to protect you and the company in future," MTV Networks said in the e-mail Friday.

Viacom said in a statement that it had "contacted appropriate law enforcement authorities, who have begun a criminal investigation."

The company also said it offered affected employees credit protection services from an outside firm, the report said.