A national consumer group yesterday asked federal regulators to investigate Herbalife, the multilevel marketing company that hedge fund manager Bill Ackman has alleged is a pyramid scheme.

In a four-page letter to Edith Ramirez, chairman of the Federal Trade Commission, the National Consumers League asked the agency to “launch an investigation to determine whether Herbalife is a legitimiate MLM [multilevel-marketer] as the company claims, or a pyramid scheme, as its detractors claim.”

Lois Greisman, head of the FTC’s fraud division, told The Post that the regulator would take the request seriously.

Herbalife was quick to attack the move.

“We regret that the National Consumers League has permitted itself to be the mechanism by which Pershing Square [Ackman’s hedge fund] continues its attack on Herbalife,” it said in a statement.