An Internet video shows what appears to be a Shell event at the Space Needle in Seattle. The video, advocated by the Twitter code #shellfail, shows a mock-up of an oil rig spewing liquid onto a bystander during the event. The video depicts Shell's sea shell logo.
A subsequent news release stated that Shell was considering legal action in response to the posted video.
Bill Tanner, senior manager for U.S. media relations at Shell Oil, told United Press International that his company was behind neither campaign.
"The video and press release were a hoax," he said.
Greenpeace, an organization describing itself as the Yes Lab and members of the Occupy movement have since claimed responsibility for the actions.
A U.S. federal court in Alaska last week issued an injunction that would keep activists from Greenpeace from Shell operations planned for the state's coast.
Shell has faced increasing pressure for its move into arctic waters. Melting sea ice is exposing areas believed to hold undiscovered oil and natural gas reserves. Shell's oil-spill contingency plans were approved by U.S. regulators.
Tanner said the company was focused on a safe and responsible exploration campaign.