The New York Police Department’s practice of stopping and frisking pedestrians in record numbers is plagued by racism and prone to excessive force, a panel of civil rights advocates and legal experts warned lawmakers yesterday.

“It’s time for the federal government to step in and protect the citizens of this city,” the Reverend Al Sharpton said at a forum in lower Manhattan held by the chairman of the House Judiciary Committee, Rep. John Conyers of Michigan.

Rev. Sharpton and other panelists advocated stricter independent oversight of the NYPD, and withholding federal funds from its coffers unless it adopts reforms to root out racism. Some also questioned why the police commissioner, Raymond Kelly, and other police officials weren’t there to respond.

“They have disrespected your chairmanship by their absence today,” Rev. Sharpton told Mr. Conyers.

Congressional aides said an invitation through City Hall to include Mr. Kelly had been turned down. Mr. Kelly’s spokesman insisted he never received one.

The event came in the wake of last month’s acquittal of three police officers in the shooting of an unarmed black man, Sean Bell, on his wedding day and amid recent reports that police had stopped about 145,000 people for searches during the first quarter of this year — the most of any quarter since the numbers were first made public in 2002.

Slightly more than 50% of the people stopped were black, while about a fourth of the city’s residents are black, according to 2006 data.

“We see a clear pattern of racial profiling in the stop-and-frisk statistics we’ve seen in the past week,” Rep. Jerrold Nadler of New York, one of several elected officials on hand to hear the testimony, said.

Mr. Nadler cited another incident involving white officers and an off-duty black police chief as evidence of possible racial problems at the nation’s largest police department.

The head of the NYPD’s Community Affairs Bureau and the highest uniformed black officer on the force, Chief Douglas Zeigler, was sitting in his department-issued SUV on a Queens street on May 2 when the two officers approached the vehicle to question him.

When Chief Zeigler got out of the vehicle, the confrontation grew testy. One of the officers was later stripped of his gun for being discourteous to a superior, officials said.

On Monday, police officials suggested the Chief Zeigler incident had been overblown. In the past, they also have defended the stop-and-frisk program as a proven crime-fighting tactic driven by descriptions of suspects and by police officers’ suspicions and observations — not by racial profiling.

Also in attendance with Rev. Sharpton yesterday were Bell’s parents, his fiancée, and one of two men who survived the hail of 50 police bullets fired at the groom-to-be’s car.

Supporters of the Bell family have called on federal prosecutors to bring civil rights charges against the shooters.

The lawmakers yesterday said the case will get a thorough review. But a former prosecutor with the Department of Justice’s Civil Rights Division, Rachel Harmon, cautioned that making a federal case can be “labor intensive and difficult to win” because prosecutors must prove police set out to violate Bell’s civil rights.

“Recklessness is not enough,” she said.