Procter & Gamble Co. is working with federal regulators to resolve operating issues at one of its plants in Puerto Rico.

The plant, which makes Olay skin care and Vicks cold medicine products, did not meet federal standards on the making and processing of over-the-counter drugs, according to an April 29 letter from the Food and Drug Administration. The letter also stated that several cosmetic products were prepared or held under “unsanitary conditions.”

P&G spokesman Paul Fox said the consumer products maker is cooperating fully with the FDA to address the issues, and stressed that all the products are safe. He said the warning letter stemmed from equipment and processes that are specific to that facility, in the town of Cayey.

“We have a very unique set of practices, procedures and equipment that we don’t see anywhere else,” he said. There is, for example, manual process at the plant that does not exist at any other P&G facility.

“While the practices are designed to meet the high standards we demand, it (the FDA) did identify potential areas where we can and will make improvements,” Fox said.

P&G had begun its own thorough investigation of the plant prior to the warning letter, following the outcome of a routine FDA inspection in the fall of 2008. In April, P&G cut 90 part-time jobs at the Cayey plant.

Cincinnati-based P&G (NYSE: PG) is the world’s largest consumer products maker, with a portfolio that includes the brands Pampers, Charmin and Gillette.