Environmental groups have opened a second legal front in their effort to require a full environmental impact statement for an interisland ferry project.

The groups filed a lawsuit in U.S. District Court last week to fight a categorical exclusion issued March 15 by the federal Maritime Administration that excludes the Hawai'i Superferry project from federal environmental laws, according to Isaac Hall, the Maui attorney representing the organizations.

"Ultimately the goal of the lawsuit is to have the exclusion set aside and to try to obtain an order that they've got to prepare an environmental assessment, at least, before they can implement the project," Hall said.

John Garibaldi, chief executive of Hawai'i Superferry Inc., said that although the project remained on track to begin operations in early 2007, the lawsuit is holding up the closing of $200 million in financing.

Hawai'i Superferry plans to operate two giant catamarans carrying 900 passengers and 250 vehicles between O'ahu and Maui, Kaua'i and the Big Island. The ferries will be able to travel at 35 knots, about 40 mph.

A lawsuit filed earlier in state court by three of the groups was dismissed in July by Maui Circuit Judge Joseph Cardoza, who said the Sierra Club, Maui Tomorrow and the Kahului Harbor Coalition didn't have standing to challenge the project. Cardoza's ruling has been appealed, Hall said.

The state-level suit challenged an environmental exemption that the state Department of Transportation granted for the project.

The three groups filed the new suit, along with Friends of Haleakala National Park.

Among other things, the groups are concerned about the impact the vessels will have on the Hawaiian Islands Humpback Whale National Marine Sanctuary and the possible introduction of alien species, Hall said.

"We're disappointed to hear that these groups are continuing to try to stop the project that brings so many benefits to the people here in the state of Hawai'i," Garibaldi said.

"We've complied with all the laws and regulations from the start of our existence, and this is just another issue to deal with."