WASHINGTON, Calif. -- The FBI is offering a reward of up to $50,000 for information leading to the arrest of four alleged environmental extremists accused of sabotage attacks in five Western states - including a 1998 firebombing at a Colorado ski resort that caused $12 million in damage.

The four are believed to be members of a radical environmental group known as "The Family" that is blamed for a series of arson attacks, vandalism and other crimes in Oregon, Washington, California, Wyoming and Colorado from 1996-2001.

The FBI identified the four as Josephine Sunshine Overaker, Joseph Mahmoud Dibee, Justin Franchi Solondz and Rebecca Rubin. The bureau said they are believed to be living outside the United States.

The 1998 firebombing at a Vail, Colo., ski resort is considered one of the most devastating ecoterrorism attacks in U.S. history. The group also is suspected in a 2001 ecoterror arson of the University of Washington's Center for Urban Horticulture in Seattle.

The incidents were among at least 25 criminal actions by members of the Earth Liberation Front and the Animal Liberation Front that caused more than $80 million in damages, officials said.

"These individuals are terrorists," said Michael Ward, deputy assistant director of the FBI's counterterrorism division.

"Regardless of their political or social message, their actions were criminal and violated federal laws."

A total of 17 people have been indicted on ecoterrorism charges related to actions by the Earth Liberation Front and the Animal Liberation Front, Ward said. Thirteen have been convicted.

The North American Earth Liberation Front press office issued a statement Wednesday calling the reward offer hypocritical.

"During the last 10 years, the federal government has wasted countless resources on its 'Operation Backfire' campaign aimed at demonizing those who are protecting the planet," said Lisa Nesbitt, a spokeswoman for the group. "Instead of tracking and prosecuting nonviolent eco-defenders, why isn't the federal government locking up the real ecoterrorists, the CEOs of corporations who are inflicting violence and destruction on the environment every day?"

The FBI said Solondz, 29, may be in Canada, Europe or Asia; Dibee, 31, in Syria; and Rubin, 35, in Canada.

Overaker, whose age is listed as 34 or 37, was born in Canada and may be living there, officials said.