NEW YORK (CNNMoney.com) - The maker of a silicone breast implant awaiting final approval from the Food and Drug Administration allegedly sought to limit leaks of silicone oil from sample implants sent to doctors' offices, but no adjustments were made to devices that would actually be implanted in women, according to a published report.

The allegation, printed in the Washington Post Monday, comes from a former senior engineer with the company, who has made his concerns known to the FDA, to a women's health group critical of the breast implants, as well as to the paper.

The whistle blower showed the paper his letter to the FDA, on the condition he not be identified due to family and job concerns.

The federal agency, which had given initial approval to the Mentor (Research) breast implant earlier this year, told the paper it is looking into the allegation.

"We are evaluating it and do take it seriously," Daniel Schultz, director of the FDA's Center for Devices and Radiological Health, told the Post.

Mentor gave a statement to the paper in which it denied there was any problem with the leakage of silicone gel from its implant. The company said the FDA letter regarding the implant's initial approval was based on safety and efficacy data that considered all aspects of the device. That data, the statement said, showed that gel leakage was "more than a million fold below toxicological levels of concern." The paper said the statement did not address whether the company made changes to the implants that were sent out as samples, but not to the devices that were to be used in women.

The Post said the company made the changes to the samples to be sent to doctors' offices for examination by patients because the implants sometimes left behind an unsettling slick of silicone oil.

The whistle blower told the paper he and others at the company were asked to solve that problem and came up with a less permeable material for the one-inch patch that seals a hole left by the manufacturing process. But he told the paper that despite urging from its staff, the company never made the same modification to the devices destined to be implanted in women.

The engineer told the paper that the low-bleed patches cost "a few pennies extra for each implant." He speculated that the company did not modify the implants due to be used in surgery out of concern that the change would jeopardize its application before the FDA.

During the April advisory panel hearing, the paper reported that an FDA staff report described three tests the company had undertaken to measure gel bleed on the implants with the original patch design. The reviewer concluded that all were of limited value in determining what might happen in the body, according to the report.

The paper reports that the whistle blower's letter to the FDA said that after it became known that he was raising concerns about the patch on the Mentor implants, the company made accusations against him that resulted in an indictment involving disputed company property.

The paper reports that the letter said he assumes Mentor "will use those accusations as their defense against the statements I have made in this letter." He said he had been advised not to discuss the accusations, but "fortunately, the statements I have made in this letter can all be checked out by the FDA."

The former Mentor engineer first took his concerns to a women's health advocate, Diana Zuckerman of the Washington-based National Research Center for Women & Families, who has been critical of the lack of long-term safety studies of breast implants.

"If it is true that the patch is low bleed for 'sizers' and high bleed for the real implants, it suggests that the company cares more about silicone oil leaking onto doctors' desks than in patients' bodies," Zuckerman told the paper.

For a look at other allegations against Mentor by former employees, click here.