The Senate Judiciary Committee has agreed to a request by Sen. Charles McC. Mathias Jr. (R-Md.) to reopen confirmation hearings on Assistant Attorney General William Bradford Reynolds after allegations by several civil rights lawyers that Reynolds was not truthful in his sworn testimony this week.

Three of the attorneys confirmed in interviews yesterday that they believe Reynolds did not tell the truth when he testified that he had met with opponents or opposing lawyers in two Voting Rights Act cases in Louisiana and Mississippi. The attorneys, all of whom were involved in the disputed cases, made the allegations in testimony before the committee Wednesday afternoon after most reporters had left the hearing.

Reynolds cited the meetings to justify his decision not to challenge election redistricting plans in the two states. The plans later were struck down in separate court actions on grounds that they discriminated against black voters.

Committee Chairman Strom Thurmond (R-S.C.) has agreed to recall Reynolds, who heads the Civil Rights Division and has been nominated for the Justice Department's No. 3 job. Thurmond, who had dismissed Reynolds Wednesday after two days of testimony, tentatively set the new hearing for June 18.

A department spokesman said that Reynolds has agreed to appear again before the committee, but declined comment on Reynolds' behalf regarding the allegations about discrepancies in his testimony.

The move could jeopardize his nomination because it comes from a Republican member of a committee on which most Democrats are strongly opposed to Reynolds and what they view as his poor four-year record of civil rights enforcement.

The allegations also raise questions about Reynolds' credibility for the first time. That is significant because some senators have indicated that in the absence of evidence of improper personal conduct, they are reluctant to vote against a qualified presidential nominee.

Mathias said in a letter to Thurmond that witnesses at the hearing "raised several significant questions" about Reynolds' record and that "the challenges are supported by citations of Justice Department documents."

A spokesman for Thurmond said that "we continue to believe the nomination is in good shape." He said Thurmond wants to provide "an opportunity for Mr. Reynolds to answer those questions and clear the air."

Frank Parker, an attorney with the Lawyers Committee for Civil Rights Under Law, said yesterday that Reynolds erroneously testified that he had consulted the attorneys for black voters in 1983 cases involving political redistricting plans in 11 Mississippi counties.

"This is flat-out wrong," said Parker, adding that he had represented black voters who successfully challenged the redistricting plans in eight of the cases. "I was never consulted by Reynolds. He never talked to me about whether the Justice Department should file these cases . . . . The nominee misrepresented the facts of this decision."

Parker said he had checked with two other lawyers who helped handle the eight private lawsuits against the county plans, and that they also had not spoken with Reynolds. He said he could not speak to the three other cases, one of which Reynolds did enter with a lawsuit.

During his committee testimony, Reynolds was asked why he did not follow his staff's recommendation and file Voting Rights Act suits in the Mississippi cases. He said:

"I talked to the private attorneys that were involved in those suits, as well as having further conversations with my staff, and it was the agreement of all of us that it made no sense for the Justice Department to come into those lawsuits, that they were already private actions pending, that we all felt that the courts were going to do what was asked in those cases, and that the involvement of the federal government at the 11th hour would probably be more disruptive than productive.

"And for that reason, it was agreed by everybody, including the staff that originally recommended I go in, and the private attorneys, that we not go into those lawsuits," Reynolds said. "And therefore I declined to file them."

The second dispute involves Reynolds' decision to overrule his staff and refuse to challenge a Louisiana congressional redistricting plan that later was struck down in federal court.

The 1982 plan, adopted after meetings between white state legislators and then-Republican Gov. David C. Treen, ruled out a majority-black district in New Orleans. Treen had vetoed an earlier plan that would have created the majority-black district; Reynolds' staff told him that a key state legislator allegedly had said that "we already have a nigger mayor and we don't need another nigger big shot."

Reynolds testified this week that he had met with opponents as well as supporters of the revised plan before deciding that it was not racially motivated and that he would not challenge it.

Lani Guinier, an NAACP Legal Defense Fund attorney who filed a successful private lawsuit against the plan, said yesterday that she had obtained Reynolds' meeting logs during the litigation. Guinier said the logs show that Reynolds met twice with Treen in 1981 and had at least nine telephone conversations with the governor in 1981 and 1982. But she said Reynolds' logs show no other meetings with persons in the case, other than his staff, and that she knows of none.

"His testimony is untrue," Guinier said.

William Quigley, an attorney who worked with Guinier in the case, said he had asked to meet with Reynolds in 1982. "We were never allowed to have a meeting," Quigley said.