FILE PHOTO : The Arleigh Burke-class guided-missile destroyer USS Fitzgerald, damaged by colliding with a Philippine-flagged merchant vessel, is seen at the U.S. naval base in Yokosuka,, Japan June 18, 2017. REUTERS/Toru Hanai/File Photo -

TOKYO (Reuters) - The U.S. Navy on Tuesday said it will haul the guided missile destroyer severely damaged in a collision with a freighter in Japanese waters back to the United States for repairs as soon as September.

The collision killed seven sailors aboard the USS Fitzgerald and ripped a hole below the vessels waterline. Naval engineers in Japan have patched up the destroyer but extensive damage that nearly sank the warship means it is unable to sail under its own steam.

“The Fitzgerald may be moved in September but it could be later than that,” a spokesman for the U.S. Seventh Fleet said.

The U.S. Navy plans to hire a commercial heavy lift ship to carry the destroyer. In the tender for the contract it has said that the furthest possible journey could be as far as to naval dockyards in Maine on the U.S. east coast.

The collision in the early hours of June 17 with a Philippine-registered cargo ship in waters close to Tokyo Bay resulted in the greatest loss of life on a U.S. Navy vessel since the USS Cole was bombed in Yemen’s Aden harbor in 2000. It has sparked multiple investigations by U.S., Japanese and Philippine authorities.

In the first detailed account from one of those directly involved in the collision, the cargo ship’s captain in a report seen by Reuters said it signaled the Fitzgerald with flashing lights around 10 minutes before the collision, but that it did not respond or alter course.