WASHINGTON -- An attorney for Planned Parenthood warned Congress on Monday that he expects the Center for Medical Progress, an undercover anti-abortion group, to release more sting videos that claim the family planning provider is engaged in illegal and racially biased activities.

The GOP-led House Energy and Commerce Committee launched an investigation into Planned Parenthood last week after the CMP released a sting video that appeared to show one of the organization's top doctors discussing the sale of fetal body parts after an abortion.

Planned Parenthood sometimes donates, but does not sell, fetal tissue for scientific research at the request of its patients, the family planning provider's attorney, Roger Evans, told the committee in a letter on Monday. He also said the CMP posed as a fetal tissue procurement company called Biomax in order to gain access to Planned Parenthood doctors and facilities, and likely has "thousands of hours of videotape" that it will "deceptively edit into short video clips to release for many months."

"We believe that on at least one occasion, a representative from Biomax was shown a highly sensitive area in a clinic where tissue is processed after abortion procedures. While this work is standard and essential during any abortion procedure, any filming in such an area would be an extremely serious invasion of our patients privacy and dignity," Evans wrote.

"We also believe that in at least one interaction at a Planned Parenthood facility, the Biomax representative asked questions about the racial characteristics of tissue donated to researchers studying sickle cell anemia." Evans said the group apparently did this "to create a misleading impression" that Planned Parenthood is targeting African-American fetuses.

Evans said impersonators posing as health care professionals also offered to pay various sums of money for fetal tissue or organs -- from $100 to $1,600 -- in an attempt to catch Planned Parenthood officials selling the tissue, but he said Planned Parenthood staff refused.

The CMP was founded by David Daleiden, an anti-abortion activist who previously worked for the group Live Action, known for its heavily edited undercover videos of Planned Parenthood staffers.

The Huffington Post reported last week that the CMP may have illegally deceived the Internal Revenue Service by applying for tax-exempt status as a biomedicine charity instead of an anti-abortion group. The ruse also worked on Planned Parenthood: The group tricked one of the provider's top doctors into discussing over salad and wine how she would preserve certain fetal parts during an abortion in order to donate them for medical research.

"The Center for Medical Progress follows all applicable laws in the course of our investigative journalism work, and we look forward to showing the public more clear evidence that Planned Parenthood routinely profits from the sale of baby parts and changes the abortion procedures it uses on pregnant women in order to do so," the group said in a statement. "Congress and state authorities are right to continue to hold Planned Parenthood accountable for these atrocities against humanity."

Evans fired back at the group in his letter to the House committee on Monday. Planned Parenthood would take "swift action" against any wrongdoing its staffers had perpetrated, he wrote, "but what we know right now is that a group of extremists who have intimidated women and doctors for years -- in their agenda to ban abortion completely -- are not 'documenting' misdeeds; they are trying to create them, quite unsuccessfully."

"Indeed, from all that is known today, it appears that the only people who have broken laws are the extremists who have been hounding women and Planned Parenthood doctors for years," Evans added.

This story has been updated to include a statement from the Center for Medical Progress.