The American branch of an international environmental group is suing two chemical companies, their PR firms, and the private investigators they hired allegedly for spying and racketteering.

“The message of this lawsuit is: when companies engage in espionage, they will be discovered and exposed. These unacceptable and underhanded tactics interfered with valuable work we were undertaking to protect public health and expose environmental crimes,” Phil Radford, executive director of Greenpeace USA, said in an advisory.

Greenpeace USA's federal lawsuit filed Monday alleges that Dow Chemical and Sasol hired a private spy firm Beckett Brown International (BBI) through public relations firms Dezenhall Resources and Ketchum to spy on the environmental group.

"Plaintiffs allege that between 1998 and 2000, Defendants conspired to and did surveil, infiltrate, and steal confidential information from Greenpeace with the intention of preempting, blunting, or thwarting its environmental campaigns," the lawsuit said.

"These unlawful activities included trespassing on the property of Greenpeace, infiltrating offices, meetings, and electronic communications under false pretenses and/or by force, and by the means, stealing confidential documents, data and trade secrets of Greenpeace," it added.

Greenpeace said that at the time the spying happened, it was spearheading a campaign with communities such as Lake Charles, Louisiana, affected by dioxin. The group alleges that a BBI operative infiltrated a local Lake Charles citizens group.

During this two year period, the PR firms and BBI, which itself is composed of former secret service agents and police officers, stole thousands of confidential documents and continued its surveillance, the lawsuit maintained.

Journalists working for Mother Jones made the group aware of the covert surveillance in 2008.

"Contained in the trove were a variety of internal Greenpeace records, including strategy memos, campaign plans, donor lists, and documents that included credit card information and the social security numbers of Greenpeace employees," James Ridgeway and Daniel Schulman wrote Monday.

The reporters also found records from other organizations, such as Friends of the Earth, GE Food Alert, the Center for Food Safety, and Fenton Communications, they said.

"While Greenpeace can only sue on our own behalf, we do so to send a message to any big corporation that plans to spy on, intimidate and interfere with communities fighting for a better world for their children," Radford said.

"When corporations hire private spies to undermine the rights of civic leaders, they are undermining democracy," he added. "We'll see them in court."

Dow, Sasol, Ketchum, Dezenhall, and BBI did not respond to reporters' requests for comment.

A recent Greenpeace report noted that the billionaire owners of privately held technology company Koch Industries funneled nearly $50 million in donations to climate change denial groups between 1997 and 2008.

The environmental activist group has set up a website promoting awareness of the lawsuit and controversy they're calling "Spygate."

Read Greenpeace's lawsuit [pdf link].