By Pedro Nicolaci da Costa 

A group of conservative activists worried the Federal Reserve has left interest rates too low for too long voiced their concerns directly to Janet Yellen, the central bank's chairwoman, during a meeting Friday.

Ms. Yellen met for about an hour in the Fed's policy meeting room with a group of 21 right-leaning economists, activists and businesspeople, said Steven Lonegan, director of monetary policy at American Principles in Action, the conservative think tank in Washington that spearheaded the meeting. Fed governor Lael Brainard was also present, Mr. Lonegan said.

The Fed declined to comment.

The group's message: The Fed has kept its benchmark short-term interest rate near zero for so long since December 2008 that the policy is now having the unintended effect of dampening employment rather than boosting it. The group said low rates encourage companies to invest in equipment and structures rather than hire more workers.

Marc Miles, economist at Global Economic Solutions in Boston and a speaker in the meeting with Ms. Yellen, said in a statement before the meeting, "low interest rates produce distortions or unintended consequences that exacerbate some of our current economic problems" like high unemployment.

This worsens the problem of U.S. income inequality, said Mr. Lonegan, who was mayor of Bogota, New Jersey for 12 years.

"We wanted to let her know it's not just the left that cares about the middle class and low-income Americans," Mr. Lonegan said in an interview after the meeting.

According to the American Principles in Action website, Mr. Lonegan is head of a project called Fix the Dollar "charged with the responsibility of building national grassroots support for sound monetary policy and restoring the gold standard."

Ms. Yellen has previously met with liberal activists at the Fed.

Republican lawmakers accused Ms. Yellen at a House Financial Services Committee hearing Wednesday of favoring Democrats, citing on her official calendar, which shows she has held more meetings over the past year with executive branch officials than with members of Congress, and met with more Democratic lawmakers than Republicans.

Rep. Scott Garrett, a New Jersey Republican, told Ms. Yellen during the hearing that her calendar, as well as her meeting with "liberal advocacy groups" and a speech on inequality, were among the factors that painted for him a picture of partisan bias. She responded it was a "complete mischaracterization" to portray her schedule and activities as partisan. She mentioned then that she planned to meet Friday with the conservative group.

Mr. Lonegan said his group supports Sen. Rand Paul's (R., Ky.) so-called Audit the Fed legislation, which would give Congress greater direct oversight on monetary policy. Proponents say it would increase central-bank transparency. Ms. Yellen repeated Thursday she strongly opposes the bill because it would threaten the Fed's independence.

Write to Pedro Nicolaci da Costa at pedro.dacosta@wsj.com