NEW YORK (AP)  -- 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 on Monday.

1010 WINS AUDIO: Juliet Papa Reports

``It's time for the federal government to step in and protect the citizens of this city,'' the Rev. Al Sharpton said at a forum in lower Manhattan held by Rep. John Conyers, D-Mich., chairman of the House Judiciary Committee.

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 Police Commissioner Raymond Kelly and other police officials weren't there to respond.

``They have disrespected your chairmanship by their absence today,'' Sharpton told Conyers.

Congressional aides said an invitation through City Hall to include Kelly had been turned down. 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 percent 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,'' said U.S. Rep. Jerrold Nadler, D-N.Y., one of several elected officials on hand to hear the testimony.

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.

Chief Douglas Zeigler, the head of the NYPD's Community Affairs Bureau and the highest uniformed black officer on the force, 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 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 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 Sharpton on Monday were Bell's parents, his fiancee and one of two men who survived the hail of 50 police bullets fired at the groom-to-be's car on Nov. 25, 2006 outside a Queens strip club. Three undercover detectives who said they believed there was a weapon in the car were cleared by a judge of manslaughter and other charges on April 25 following a bench trial in Queens.

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

The lawmakers on Monday said the case will get a thorough review. But panelist Rachel Harmon, a former prosecutor with the Department of Justice's Civil Rights Division, 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,'' said Harmon, now a University of Virginia law professor.