Malaysia Airlines Flight 17 was likely struck by multiple "high-energy objects from outside the aircraft," causing it to break up over eastern Ukraine, a preliminary report into the deadly aviation disaster concluded Tuesday.

The report by the Dutch Safety Board stopped short of saying the Boeing 777 was shot down by a missile, but its findings appear to point to that conclusion. It also did not say who might have been responsible.

The Boeing 777 suddenly plunged out of the sky July 17 over pro-Russian rebel-held territory in Ukraine, killing all 298 passengers and crew on board.

"The damage observed in the forward section of the aircraft appears to indicate that the aircraft was penetrated by a large number of high-energy objects from outside the aircraft," the report said. "It is likely that this damage resulted in a loss of structural integrity of the aircraft, leading to an in-flight break up."

The board is leading the international investigation into the cause of the disaster. Its full report is expected within a year of the crash.

"The initial results of the investigation point toward an external cause of the MH17 crash," the board's chairman, Tjibbe Joustra, said in a statement. "More research will be necessary to determine the cause with greater precision. The Safety Board believes that additional evidence will become available for investigation in the period ahead."

Because of the ongoing conflict between pro-Russian rebels and Ukrainian forces, investigators from the board have not visited the fields where the wreckage of Flight 17 plunged to the ground. That likely contributed to the board's cautious assessment of what happened.

"Detailed examination of the structural damage is ongoing," the report said. "Forensic examination will be performed if the wreckage can be removed."

Investigators so far have studied photos of the crash site, radar data and information gleaned from the downed jet's "black boxes" -- its cockpit voice recorder and flight data recorder. They all indicated that there was no technical fault that may have caused the plane to disintegrate.

The cockpit voice recorder "revealed no signs of any technical faults or an emergency situation," the Safety Board said. "Neither were any warning tones heard in the cockpit that might have pointed to technical problems."

Pro-Russian rebels officially deny having shot down the plane, but unofficially one senior rebel admitted they were behind a missile strike.

Just three hours before the plane was shot down above rebel-held territory in Eastern Ukraine, the Associated Press reported on the passage of a Buk M-1 missile system -- a machine the size of a tank bearing four ground-to-air missiles -- driving through the rebel-held town of Snizhne, near the crash site.

A highly placed rebel officer told the AP in an interview in the aftermath of the disaster that the plane was shot down by a mixed team of rebels and Russian military personnel who believed they were targeting a Ukrainian military plane.

Intercepted phone conversations between the rebels released by the Ukrainian government support that version of events.

In those tapes, the first rebels to reach the scene can be heard swearing when they see the number of bodies and the insignia of Malaysia Airlines.