Washington  - US President Barack Obama condemned the murder of an abortion doctor who was shot down inside a Wichita, Kansas, church early Sunday, throwing the national spotlight on the decades-old bitter struggle over the issue.

George Tiller, 67, one of the country's few physicians who performed late-term abortions, was apparently shot in the head in the foyer of the Reformation Lutheran Church as he was serving as an usher for Sunday morning services, according to media reports.

Tiller, who was injured in 1993 in an attempt on his life, reportedly wore a bullet-proof vest to church that morning, as he often did in his travels around the community.

A 51-year-old suspect was arrested 180 kilometres away from the murder site, Wichita Deputy Police Chief Tom Stolz said, according to the Kansas City Star online.

"We think we have the right person arrested. We're going to get him charged," Stolz said in broadcast remarks. The suspect faces one charge of murder and two of aggravated assault after he threatened two other church-goers with his gun.

Tiller is the eighth fatal victim of a violent assault by abortion protestors since 1993, according to statistics kept by the National Abortion Federation (NAF), the professional association of abortion providers in the United States and Canada.

Since the US Supreme Court ruled in 1973 that a woman's decision about abortion was protected by constitutional privacy guarantees, federal police have become involved in investigating such murders, attempted murders and hundreds of bombing and arson attacks on abortion clinics.

US Attorney General Eric Holder said that federal law enforcement officials were coordinating with local police. He directed US Marshals to "offer protection to other appropriate people and facilities around the nation."

Obama, a centre-left Democrat who supports access to legal abortion, took the unusual step of commenting on the killing. Earlier this month, he signalled his willingness to grapple with the issue in a graduation speech at a Catholic university and appealed for both sides to work together to help women facing unplanned pregnancies.

Obama said he was "shocked and outraged" by Tiller's murder.

"However profound our differences as Americans over difficult issues such as abortion, they cannot be resolved by heinous acts of violence," the president said in a statement.

The issue of late term abortion is used graphically by anti- abortion groups to promote their cause. In addition, there is debate over the definition of "late term," generally seen as the 21st to 27th week of pregnancy, depending on whether the fetus is viable.

According to the Centers for Disease Control, 59 per cent of all US abortions in 2002 occurred before the eighth week of pregnancy; 33.3 per cent between 9 and 15 weeks; 4 per cent between 16 and 20 weeks; and 1.4 per cent after 20 weeks.

Tiller once said that third trimester abortion - the lst 12 or 13 weeks - was "simply a part of abortion," according to an interview broadcast from CNN's archives. He said however that if a doctor determined the fetus could live on its own outside the womb, the operation would not be performed.

Tiller performed late term abortions "almost always in circumstances where something had gone horribly wrong with a pregnancy," according to Peter Brownlie, president of the Kansas City-based regional Planned Parenthood office, who was quoted by CNN.

Tiller's murder comes less than a week after Obama nominated his first candidate for the Supreme Court, Sonia Sotomayor, a moderate left-leaning federal judge whose possible position on abortion will be closely, if discretely, weighed by the US Senate, which must give approval to the life-long position.

Tiller's clinic had been targeted by bombs, shootings and vandalism over the years in Kansas, a stronghold of the anti-abortion movement.

The killing brought an outpouring of condemnation from both sides.

Nancy Keenan, president of NARAL Pro-Choice America, said Tiller's murder sent "a chill down the spines of the brave and courageous providers and other professionals who are part of reproductive-health centers that serve women across this country."

The feminist organization National Organization for Women called it a "cold-blooded murder" and an act of "domestic terrorism."

Anti-abortion groups also deplored the shooting.

Mary Kay Culp, executive director of Kansans for Life, said her organization was "shocked and very upset by what happened in Wichita," adding that they "value life" and "completely deplore violence."

Another anti-abortion group, Operation Rescue, denounced "vigilantism and the cowardly act that took place this morning." (dpa)