WASHINGTON (Reuters) - Lockheed Martin Corp on Monday said there was no evidence that a lithium-ion battery contributed to a February 14 incident that caused smoke in the cockpit of an F-35 test plane.

Lockheed spokesman Michael Rein said initial reviews indicated a potential failure in the plane's cooling system, which had been removed from the aircraft for further study.

"The battery was not one of the components pulled from the aircraft for further review. There is no evidence that the lithium ion batteries are a contributor to this event," Rein said, adding, "No battery faults were observed at any time."

The Pentagon on Monday said it was shipping the plane's "power thermal management system" back to its manufacturer, Honeywell International Inc. The system uses a lithium-ion battery similar to those whose failures have grounded Boeing Co's entire fleet of 787s, but the Pentagon said there was no connection between the F-35 incident and its batteries.

(Reporting By Andrea Shalal-Esa; Editing by Gary Hill)