Environmentalists are challenging the Richmond City Council's decision to approve Chevron Corp.'s plans to upgrade its Bay Area oil refinery.

In a lawsuit filed Thursday, three environmental groups claim the city's environmental review concealed that the project would lead to more air pollution and higher risks for major accidents and oil spills.

Despite strong opposition, the city council voted 5-4 in July to approve a permit for Chevron to replace old equipment, build a new power plant and make other changes at its Richmond refinery.

In exchange, the San Ramon-based oil company offered the city $61 million for programs to help the community.

The Richmond City Attorney's office says it hasn't seen the complaint and can't comment.

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