Todd Akin, the Republican US Senate nominee from Missouri, stood by his latest comment over abortion on Wednesday, as physicians' groups condemned them as "part of an old-fashioned narrative" that presumed women are gullible and abortion doctors unethical.

Akin's claim that abortion doctors are "terrorists" who perform the procedure on women who aren't pregnant was made several years ago, on the floor of the House of Representatives. It resurfaced on Monday, two months after Akin caused a furore when he claimed that victims of "legitimate rape" could "shut down" potential pregnancies.

On Wednesday, his campaign released a statement from a former director of Planned Parenthood, now a pro-life advocate, who attempted to back him up and said that they often "scared women" into having abortions, including women who were not pregnant and those who were miscarrying, in order to collect the fees.

Dr Nancy Stanwood, the board chair-elect of Physicians for Reproductive Choice and Health, and an obstetrician, said: "Congressman Todd Akin has already proved he is not an authority on women's health."

She said his latest comments played into a false narrative "which had no place in the 21st century, that women who have abortions are gullible and doctors who perform them are schysters and quacks".

Stanwood said that doctors who perform abortions, herself included, are wrongly stigmatised and under greater scrutiny than other medical professionals. Akin was "incredibly poorly informed and most Americans recognise that".

"We're thoughtful and passionate, and we've worked really hard to get the medical training we need to take care of patients. That's our motivation, and that's the 21st century narrative that we want people to pay attention to."

She said she didn't know what he could even have been referring to. "I'm not quite sure of the meaning. It's hard to put it into any medical context because it's not medical."

A Planned Parenthood spokeswoman in Missouri told the Associated Press that Akin's assertion was "an absolutely ridiculous claim" and that the agency's clinics never perform abortions on women who aren't pregnant.

In the video clip shown on C-Span and first published by Slate on Tuesday, Akin said that doctors who perform abortions are "terrorists" who work in places mired in a "culture of death."

"Along with this culture of death go all kinds of lawbreaking" he said. "Not following sanitary procedure, giving abortions to women who aren't actually pregnant, cheating on taxes, all these kinds of things. The misuse of anesthetics so that people die or almost die. All of these things are common practice and all that information is available for America."

When asked by the Guardian what Akin was referring to, Rick Tyler, his spokesman, said there were "a number of documented cases" where doctors have deceived women into thinking they were pregnant and then charge them for an abortion. He referred to a Chicago Tribune investigation in 1978 as evidence that doctors trick women into having abortions and then collect fees for a procedure they don't perform.

Tyler said nobody hears about this happening anymore because the problem is no longer talked about. "From my perspective there's lots of things about abortion clinics that don't get reported at all. When an abortion goes badly, when doctors have to call 911. Why are the abortions mostly girls? What about the high number of black babies being aborted?"