Financial firms warned of Al Qaeda cyber-threat

The government has warned U.S. private financial services of an Al Qaeda call for a cyber-attack against U.S. online stock trading and banking websites beginning today, officials said Thursday.

The officials -- a person familiar with the warning and a spokesman for the Department of Homeland Security -- said the Islamic militant group aimed to penetrate and destroy the databases of the U.S. stock market and banking websites.

The Department of Homeland Security said it had no evidence to corroborate the threat but had issued the warning out of an "abundance of caution."