Story highlights The warship was towed to deep water last week to begin the loading process

"Repairs are expected to extend the on load process by a few days," according to a Navy statement

Washington (CNN) The USS Fitzgerald, a Navy destroyer that was damaged in June after a deadly collision with a cargo ship off the coast of Japan, suffered two punctures to its hull on Sunday while being loaded onto a transport ship destined for the US, according to the service.

Already crippled as a result of the June 17 collision that killed seven US sailors, the Arleigh Burke-class guided missile destroyer was headed to Mississippi for repairs but was forced to return to its home port in Yokosuka, Japan, when it sustained additional damage in an incident involving a heavy lift transport vessel called the Transshelf.

The Arleigh Burke-class guided-missile destroyer USS Fitzgerald is loaded onto heavy lift transport MV Transshelf last week off Yokosuka, Japan.

"Fitzgerald returned to repair two punctures in her hull caused by the heavy lift vessel's steel support structure during on load at anchorage," the US Navy 7th Fleet said in a statement

"Repairs are expected to extend the on load process by a few days, after which Transshelf will transport Fitzgerald to Huntington Ingalls Industries in Pascagoula, Mississippi, for further repairs and upgrades," the statement said.

The warship was towed to deep water last week to begin the loading process while en route back to the US for repairs after the collision earlier this year caused significant damage to its starboard side above and below the waterline.

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