(CNN) -

Dutch investigators will issue a preliminary report Tuesday on the crash of Malaysia Airlines Flight 17, which was shot down in eastern Ukraine in July.

The Dutch Safety Board said its report will be based on the sources available.

A further investigation will be needed before a final report is issued, the board said in a statement on its website. The final report is expected within a year after the crash.

The Boeing 777 fell from the sky on July 17 near the Ukraine-Russia border. Of the 298 people killed, a majority were Dutch.

It's unclear who shot it, but the U.S. and Ukraine have accused pro-Russian separatists operating in the region of downing the plane with a missile.

After the crash, the separatists took control of the site for weeks, combing through the wreckage and hindering access to investigators.

The plane was headed from Amsterdam, Netherlands, to the Malaysian capital of Kuala Lumpur.