Scott Roeder argued that he shot Dr Tiller in order to save unborn babies

A man who said he killed a US abortion doctor in Kansas to save the lives of unborn babies has been found guilty of first-degree murder.

Scott Roeder had pleaded not guilty to murder, arguing that he committed manslaughter to prevent a greater harm.

He shot George Tiller, one of few late-term abortion providers in Kansas, at his church in Wichita on 31 May, 2009.

Roeder, 51, faces life in jail with the possibility of parole after 25 years. He is due to be sentenced on 9 March.

The jurors took only 37 minutes to find him guilty of first-degree murder.

He was also convicted of aggravated assault for pointing a gun at two church ushers after shooting Dr Tiller.

Clinic targeted

Roeder's lawyers had hoped he would face a lesser charge of voluntary manslaughter.

But Judge Warren Wilbert ruled that that charge could not be considered because abortion, including the late-term abortions conducted by Dr Tiller, 67, was legal in Kansas.

George Tiller had been providing abortion services since the early 1970s

The judge also ruled out a second-degree murder conviction, which does not involve premeditation.

On Thursday, Roeder told the court in Wichita: "I did what I thought was needed to be done to protect the children. I shot him."

"If I didn't do that, the babies were going to die the next day."

The BBC's Adam Brookes, in Washington, says that because Dr Tiller performed abortions, and late-term abortions in particular, he had been a target of anti-abortion activists for many years.

His clinic was one of only three in the US that offered what are known as late-term abortions, performed after 21 weeks.

It was heavily fortified after a bomb attack in 1986. Dr Tiller also survived an attempt on his life in 1993.