Mayor Marion Barry, staking out a leading position on the issue of violence against abortion clinics after a bombing Tuesday at a Southeast Washington facility, sharply criticized the FBI yesterday for not taking over the investigation of the incidents.

Barry also escalated his verbal battle with antiabortion leaders over whether the right-to-life movement has been quick enough or strong enough in denouncing the spate of bombings, and took credit for pushing the Rev. Jerry Falwell into his strongest condemnation to date of the bombings.

"I think the FBI has to be more vigorous in here," Barry told reporters, after his joint television appearance with Falwell on the CBS Morning News to discuss the bombings. "I know they're on the edges of it . . . but they ought to really probably take the lead.

"You could assume that these explosives are transported interstate, and it's easy for the FBI to get into it," Barry said. "They've gotten into things before. You assume the products used to make these bombs are transported interstate. Any time a person crosses a state line to commit a crime, that gives the FBI jurisdiction."

Meanwhile, an imprisoned leader of an antiabortion group called the Army of God sent a Christmas letter to supporters inviting them to use the group's name in their antiabortion activities and boasting that the Army of God was responsible for "229 pickets and other activities against death chambers across the nation."

A man who who said he was part of the Army of God called The Washington Times on Tuesday and claimed responsibility for the latest blast, at the Hillcrest Women's Surgi-Center at 3233 Pennsylvania Ave. SE.

The investigation is being headed by the U.S. Treasury Department's Bureau of Alcohol, Tobacco and Firearms (ATF), which has primary jurisdiction. A spokesman for the FBI said yesterday that his agency is doing everything it can to assist in the investigation, but Barry argued that the FBI should step in and take over.

Lane Bonner, the FBI spokesman, said yesterday that since 1973 the ATF has had primary responsibility for investigating cases involving the use of explosives and has assigned 500 agents to those investigations -- far more than are assigned to the FBI's antiterrorism unit.

The FBI has aided the ATF in its investigations of bombings at clinics by providing information from the agency's Bomb Data Center and behavioral science unit, according to Bonner. Also, FBI agents have been instructed to stay abreast of bombing investigations and offer whatever services they can, Bonner said.

"It's not a matter of being on the fringe," Bonner said. "We're working very closely with ATF and the Justice Department."

Technically, the FBI's special antiterrorism unit could enter a case if law enforcement officials determined that a bombing or other act of violence was part of an organized terrorist attack. However, FBI Director William H. Webster has expressed reluctance to characterize the bombings of abortion clinics as terrorism.

"I think we make a mistake in trying to worry about semantics," Webster said last Sunday while being interviewed on CBS's "Face the Nation" program. "Because if someone wants to call this a terrorist act in semantical terms, I'm not going to quarrel with it. It's wrong. It's legally indefensible. And we are doing something about it."

Barry and Falwell, a leading opponent of abortion, met yesterday morning on television to debate the mayor's assertion after Tuesday morning's bombing that "the Jerry Falwells of the world" haven't done enough to condemn the growing violence.

Goaded by Barry and anchorman Bill Kurtis, Falwell agreed that the bombings were acts of terrorism, the strongest language the Moral Majority leader has used to date in discussing the violence.

But Falwell complained that the mayor had overlooked or ignored his previous public statements against violence, and also criticized Barry, a former civil rights activists, for not speaking out against the rioting and violence of the late 1960s, after the assassination of civil rights leader Martin Luther King Jr.

"I don't recall the mayor calling people who, after Martin Luther King was killed and Watts, and all the streets were on fire and they were looting, I don't remember him calling those persons terrorists," he said.

Falwell also said that the rash of bombings and violence against clinics, including 24 incidents in 1984 alone, stemmed from what he called the equally criminal act of abortion.

"While you cannot condone the behavior of those who do any violent act, at the same time I come back to my former statement . . . that I do believe that unborn life is sacred and that the destruction of unborn life is also a crime."

After the program, Barry took credit for raising the public's conscience about the mounting violence and for forcing Falwell to condemn the bombings as terrorism. However, he also criticized Falwell for trying to cloud the issue and hedge his condemnation.

"I don't think you can appear to condone or even hedge on the question of terrorism and violence," he said.

So far, the call to The Washington Times is the only publicly revealed clue in the latest bombing incident.

However, ATF spokesman Tom Hill yesterday discounted the importance of the call. He said the bureau believes that only three men -- all currently in prison -- belong to the Army of God, including Don Benny Anderson, the leader who is serving a 43-year sentence in federal prison in Oxford, Wis., for bombing a Fairfax County gynecological clinic and burning two Florida abortion clinics.

The two others are Matthew and Wayne Moore, two brothers who are also serving time in a Colorado federal prison in connection with the Florida fires.

Anderson sent a Christmas letter to supporters inviting them to use the group's name in their antiabortion activities, according to an antiabortion leader in Chicago who said he received a copy of the letter.

"The Army of God is fast becoming a living saga of love and courage . . . ," Anderson wrote in the two-page, hand-written letter. "All fighting for righteousness are God's Army and can use the name."

"I don't think that people would take up the name just because Don sent them a card, but I don't know, maybe he's encouraging them," said Joseph M. Scheidler, executive director of the Chicago-based Pro-Life Action League, who said he received a copy of the letter. "It scares people off if you leave a note that says the Army of God. It sounds real sinister."

Members of two leading prochoice groups -- the National Abortion Rights Action League and the National Abortion Federation (NAF), whose office was bombed last year -- yesterday echoed Barry's call for an FBI investigation of the rash of abortion clinic violence.

The FBI's decision not to take over the investigation "says that they haven't for whatever reason gotten a directive that this is of enough importance to initiate a national investigation," said NAF Executive Director Barbara Radford,. "We suspect that if we were talking about a chain of supermarkets that had been bombed to the extent of 29 in one year that we would see an FBI investigation."