The U.S. Food and Drug Administration (FDA) is calling for further inspection and an outside audit of a Johnson & Johnson unit following manufacturing lapses.

The FDA, in a warning letter made public on Tuesday, cited multiple problems at Advanced Sterilization Products, a division of J&J's Ethicon, including failures to verify design changes needed to make sure devices work properly. The division also did not ensure that finished devices met necessary requirements, among other violations, the FDA wrote March 12.

The Irvine, Calif.-based division makes various sterilizers and cleaning devices, including Sterrad, Evotech and Cidex products, according to the agency. The company's responses to the FDA so far have been inadequate, the agency said.

In a statement, J&J told Reuters that Advanced Sterilization Products "has aggressively implemented a number of specific corrective actions to address deficiencies in some of our internal processes" and would continue to work with the FDA. It also noted that the letter did not prohibit the company from selling its products, which it said were safe and effective when used as directed.

The FDA said a follow-up agency inspection of the Johnson & Johnson unit will be required. It also requested an audit and certification by an outside expert consultant. FDA's letter was posted on the agency website.