Washington (AFP) - Websites at several major US airports were briefly down on Monday, following cyber attacks instigated by a pro-Russian hacking group.

The "Distributed Denial of Service" (DDoS) attacks targeted the websites of airports in Atlanta, Chicago, Los Angeles, New York, Phoenix and St. Louis.

Distributed denial-of-service attacks flood websites and servers with erroneous traffic and confuse them, impairing their functionality or completely disabling them.

The attacks on US airport websites began after the pro-Russian hacking group KillNet published a list of targeted sites and encouraged its supporters to attack them.

The electronic attacks affected websites that provide services to travelers only and not those concerned with operations.

Hartsfield-Jackson Airport in Atlanta said its site was "returned to operation after an accident early this morning rendered it unavailable to the public."

"An investigation is underway into the accident," he added, noting that operations at the airport were not affected at any time.

It appeared that most of the targeted airport sites returned to work normally after they were temporarily suspended from connecting to the Internet.

Last week, the Killnet group claimed responsibility for attacks on a number of US government websites, as well as those of other countries opposed to Russia's invasion of Ukraine.
There was no immediate comment from the US Cyber and Infrastructure Security Agency.