A US doctor who performed late-term abortions has been shot dead during a morning church service in Wichita, Kansas.

Dr George Tiller, 67, was serving as an usher for the service at the Lutheran church on Sunday morning when he was shot, reports the BBC.

Police have charged 51-year-old Scott Roeder with first-degree murder and two charges of aggravated assault for pointing the gun at other people present at the time.

Dr Tiller's clinic, Women's Health Care Services, is one of only three in the US that perform abortions after the 21st week of pregnancy. It was often the target of demonstrations and attacks by opponents of late term abortion. He survived an attempt on his life 16 years ago when Rachelle Shannon shot him in both arms outside his clinic and just last month, vandals caused thousands of dollars' worth of damage by putting a hole in the roof to allow rain water in.

A statement from Dr Tiller's family described his murder as an "unspeakable tragedy".

"This is particularly heart-wrenching because George was shot down in his house of worship, a place of peace."

His murder has also been condemned by pro-life campaigners.

Troy Newman of Operation Rescue, an organisation that campaigned for years to close down Dr Tiller's clinic, said: "We denounce vigilantism and the cowardly act that took place this morning."

President Barack Obama also condemned the killing, saying: "However profound our differences as Americans over difficult issues such as abortion, they cannot be resolved by heinous acts of violence."