The man who went undercover to expose how Planned Parenthood profits from selling body parts of aborted babies said the abortionist organisation should be held liable for committing "atrocities against humanity."

Investigator David Daleiden said he and his fellow members of the Center for Medical Progress (CMP) undertook the "Human Capital" investigation for 30 months to be able to show the public what really takes place in the abortion industry.

"We need to hold Planned Parenthood responsible for their atrocities against humanity. These videos are to inform and activate the public about what is going on right under our noses — with taxpayer dollars," Daleiden said.

"It is as if they are going on a treasure hunt for the heads or hearts of babies, but how much more valuable would those heads and hearts be if they were allowed to grow up and be a part of society?" Daleiden said.

During the course of their investigation, Daleiden and members of his team secretly videotaped Planned Parenthood officials haggling over the price of aborted baby parts.

In the second video uploaded by the team, Planned Parenthood's Medical Directors' Council president Dr. Mary Gatter is seen asking for at least $75 per specimen, and even demanding a Lamborghini on top of the payment.

Daleiden and the other investigators pretended to be members of a fictitious biotechnology company interested in procuring body parts of aborted babies.

"No one ever suspected anything. I'm sure they got the surprise of their careers the morning they woke up and saw the video," Daleiden said.

Because of the exposé by Daleiden's team, 50 Republican senators have already called for an investigation to find out if Planned Parenthood violated the federal law banning the commercial sale of foetal tissue.

"The footage raises a number of questions about the practices of the organisation, including whether they are in compliance with federal laws regulating both the use of foetal tissue and partial-birth abortions," the Republican senators said in a letter to Health and Human Services Secretary Sylvia Matthews Burwell.