The global hacker group Anonymous is claiming it has broken into the e-mail servers of five oil and gas companies involved in drilling in the Arctic Ocean and posted hundreds of employee e-mail addresses and passwords online.
The hacking reportedly targeted Russia's Gazprom and Rosneft, as well as Exxon, BP, and Shell.
The energy companies have not commented on the Anonymous claim.
It marks the second Anonymous attack on the same firms in less than a month.
An Anonymous hacker identifying himself only as @le4ky said the attack is a gesture of support for the Greenpeace environmental group, which has launched a campaign to protect the Arctic shelf from energy exploration.
Greenpeace praised the Anonymous campaign in June after the group hacked and released data about Exxon employees.
Based on reporting by "The Moscow Times" and RFE/RL's Tom Balmforth in Moscow