Attorneys for two environmental groups have filed an amendment to their lawsuit charging that the city of Oakland approved a 54-acre Oakland Zoo development for the wildland areas of Knowland Park in violation of an act that requires geologists to map out seismic hazard zones.

In July, the Friends of Knowland Park and the East Bay Chapter of the California Native Plant Society filed a lawsuit against the city and the zoo to stop the zoo's plans to expand about 54 acres into undeveloped Knowland Park to build a veterinary hospital, new animal exhibit, aerial gondola, camping area and an educational-interpretive center.

The environmental groups originally sued the city and the zoo on the grounds that they broke the law by approving the project without a full Environmental Impact Report.

Zoo officials say they did complete the required environmental review process and that the Oakland Parks and Recreation Advisory Commission, Planning Commission and City Council approved the project after lengthy open discussions and community meetings.

Last week, attorneys for the two groups filed what is called an amended legal petition in Alameda County Superior Court, charging that under the Seismic Hazards Mapping Act, a geotechnical report must be submitted to the state before approval of a project in a mapped earthquake area.

Nik Dehejia, the zoo's director of strategic initiatives, said the zoo is "deeply disappointed" that the environmental groups are continuing the litigation.

"This new amendment, like all their other claims, is without merit," said Dehejia, adding that the conditions of approval, including those related to geotechnical conditions, meet state and local laws.

The environmental groups say the issue of the seismic hazards was raised publicly in March, but the City Council approved the project anyway.

"The northern half of the planned (interpretive center) building and at least three of the eight independent gondola support structures lie within a defined seismic hazard zone," said Ruth Malone, co-chairwoman of Friends of Knowland Park. "These defined zones were specifically developed by state law to help protect the public. Waiting until after a project is approved to prepare these reports makes no sense."