MOUNTAIN VIEW, Calif. — Google, under federal investigation over alleged “extreme” pay discrimination against women, has just been hit with a lawsuit claiming it systematically pays women less than men.

The legal action by three female employees seeks class-action status to cover all women employed by the Mountain View search giant in the past four years.

“Google has discriminated and continues to discriminate against its female employees by systematically paying them lower compensation than Google pays to male employees performing substantially similar work under similar working conditions,” said the lawsuit, filed Thursday in California Superior Court in San Francisco.

The women’s lawyer, James Finberg, said Thursday that his team will rely heavily on testimony from U.S. Department of Labor hearings.