By Susan Heavey

WASHINGTON (Reuters) - U.S. health regulators have warned Philips Medical Systems Inc about a host of problems with its manufacturing procedures at an Ohio plant, including a failure to oversee proper device design, according to a letter released on Tuesday.

U.S. Food and Drug Administration inspectors visited Philips' Cleveland plant in September and October 2007 and found more than a dozen production problems at the facility, which makes computed tomography (CT) and nuclear medicine devices.

Among them were an inadequate system to manage production changes and problems with software to check devices, the FDA said in an April 1 letter to Philips Medical Systems, a unit of Philips Electronics NV (PHG.AS: Quote, Profile, Research) (PHG.N: Quote, Profile, Research).

The letter, released on the FDA's Web site on Tuesday, also said the company did not properly maintain certain investigative records and failed to set up proper procedures to handle complaints.

"Your procedure does not require systematic evaluation to determine if an event is ... reportable," the FDA said.

Since the inspection, Philips Medical has taken some steps to correct the problems but has not addressed all of them, the FDA said.

Philips spokesman Arent Jan Hesselink said the company has resolved 10 of the 14 FDA complaints.

"On the remaining four, we are still working with them. It is a matter of implementing some changes, in some cases simply a matter of providing the FDA with documentation," the spokesman said.