Malaysia Airlines Flight 17 was downed over eastern Ukraine by a Buk missile brought in from Russia and fired from a village under the control of pro-Russian separatists, a team of international prosecutors said Wednesday.

Speaking at a press conference in the Dutch city of Nieuwegein, Wilbert Paulissen, the head of the Dutch National Detective Force, said there was conclusive evidence that a missile from the Russian-made Buk 9M38 missile system downed the passenger flight on July 17, 2014, killing all 298 people on board.

The Buk was returned to Russian territory the next day, said Paulissen, presenting the findings of the Joint Investigation Team (JIT), a Dutch-led group of prosecutors gathering evidence for a potential criminal trial into the downing of MH17.

"We have no doubt whatsoever that conclusions we are presenting today are accurate," he said.

Ukraine's Ministry of Foreign Affairs said the findings pointed to the "direct involvement" of Russia, and said an investigation was ongoing into specific suspects and their "place in the chain of command" in order to pursue a criminal case.

ussia, which has repeatedly denied any involvement in the downing of the plane, rejected the report.

"None of the missile complexes, including BUK, have ever crossed Russian-Ukrainian border," said Russia's spokesman for the Ministry of Defense, Igor Konashenkov, in a statement.

"All data presented today is based upon two sources -- the Internet and Ukrainian security services. That's why the objectivity of this data, and so of all the conclusions made based on it, leaves us with doubt."

(CNN)