(Adds background, further comment from Army)
WASHINGTON, Sept 11 (Reuters) - The U.S. Army on Friday said it had issued a stop-work order to Oshkosh Corp on a contract valued at up to $6.75 billion for 17,000 new armored trucks, following a protest filed against the contract award this week by Lockheed Martin Corp.
Army spokesman Michael Clow said the stop-work order, or "stay of contract performance," was required under federal procurement law.
Lockheed on Tuesday said it filed a formal protest against the Oshkosh contract with the Government Accountability Office, which must rule on the case by Dec. 17. The other losing bidder, privately-held AM General, which built the U.S. military's original Humvees, did not file a protest.
Clow said the Army remained confident that the new Joint Light Tactical Vehicle (JLTV) to be built by Oshkosh would provide soldiers and marines a substantial capability improvement at an affordable price.
Oshkosh shares were down 0.8 percent in late Friday trading.
(Reporting by Andrea Shalal; Editing by Nick Zieminski)