A Dutch-led investigative team said Wednesday that the surface-to-air missile that downed a passenger jet over eastern Ukraine in 2014, killing all 298 people aboard, came from Russia and was fired from territory held by pro-Moscow separatists.

Investigators stopped short of directly accusing Russia of complicity in the attack on the Boeing 777 and declined to name any suspects publicly. But the briefing was seen in Russia and in the West as a virtual indictment of Moscow, prompting Russian protests as ­investigators said they would continue trying to determine who ordered the strike.

Both Russia and the rebels in Ukraine deny any role in the July 2014 attack on Malaysia Airlines Flight 17, which was traveling from Amsterdam to Kuala Lumpur, the Malaysian capital.

The findings are intended to be used in a possible criminal trial. But even if suspects are identified, it is unclear how they would be apprehended, especially if they are in Russia or in separatist-held Ukrainian territory.

The investigators concluded that the plane was shot down with a missile launched from what the Russians call a Buk TELAR battery, said Wilbert Paulissen, a senior investigator in the Dutch national police.

The missile launch vehicle “was brought in from the territory of the Russian Federation and after launch was subsequently returned to Russian Federation territory. This conclusion is based largely on forensic investigation,” he said.

The system thought to be used in the missile firing — four ­surface-to-air missiles mounted on a launch vehicle — was smuggled into Ukraine from Russia just hours before the missile was fired, the investigators said at a news conference in Amsterdam. The launch system, also known as an SA-11 “Gadfly,” was returned to Russia the day after the attack, which left bodies and wreckage strewn across farms and fields of sunflowers.

The U.S. State Department said the findings matched those made by American officials, and British Foreign Secretary Boris Johnson said that “we ask that Russia now engages constructively with the findings and ongoing investigation.”

The evidence was based on intercepts of telephone conversations between separatist fighters in eastern Ukraine, as well as open-source photographs, eyewitness accounts and satellite data, investigators said. Much of the material was first identified by online activists and citizen journalists, including the influential Bellingcat.com website, which has been targeted by Russian government hackers, according to reports.

While a previous Dutch-led safety inquiry had said the missile was most likely launched from separatist-held territory, Wednesday was the first time that investigators said it had been transported across the border from Russia.

The team members said that they had identified more than 100 people linked to the downing of the plane and that they would seek to identify “who ordered the plane to be shot down.” The investigation has been extended into 2018.

No venue has been given for a possible trial.

Moscow has maintained that it has not backed the separatists at all, much less supplied them with a modern antiaircraft missile system that requires a trained crew. On Monday, Russia said it had radio location data that implicated Ukraine’s government in the attack and ruled out the launch of a missile from separatist-held territory.

On Wednesday, Russia’s Foreign and Defense ministries, and Almaz-Antey, the manufacturer of the Buk missile system, all declared the investigation biased and dismissed some of the evidence presented.

“All the data presented today at the briefing of the investigative group have two main sources: the Internet and the Ukrainian security services,” said Maj. Gen. Igor Konashenkov, a Russian military spokesman. “Thus the objectivity of the information, and the subsequent conclusions made on it, must summon doubt.”

In Ukraine, separatist leaders on Wednesday denied the evidence presented in the report, saying that they did not have access to sophisticated surface-to-air missiles, and they accused Ukraine’s government of the attack.

Dutch investigators suggested Wednesday that the Buk may have been transferred to Ukraine to protect separatists from Kiev’s aerial attacks during intense fighting in the summer of 2014. Pro-separatist websites initially announced the attack on the passenger jet as a successful strike against a Ukrainian military plane.

The investigators, citing intercepted telephone calls and social-media photos, said that the trailer carrying the Buk missile system crossed into Ukraine from Russia on the morning of July 17, the day of the attack, accompanied by a jeep and minivan carrying separatist fighters. Video and photographs showed the missile system that day in Donetsk, the largest city held by the separatists, and then traveling toward the villages of Snezhnoye and Pervomaiskiy.

The missile “without any doubt” was launched from a field in the farmland near Pervomaiskiy, a video made by the investigators said, citing witnesses who gave testimony and showing pictures of a smoke trail coming from the field.

The missile launcher was subsequently driven back across the Russian border early the next morning on a Volvo truck, judging by videos and intercepted telephone calls, the investigators said.

The Dutch-led investigative team includes representatives from Australia, Belgium, Malaysia and Ukraine. Relatives of those killed in the attack were informed of the conclusions earlier Wednesday. Of the victims, 193 were Dutch citizens, 43 were from Malaysia and 27 were from Australia. Citizens of the United States, Belgium, Britain, Canada, Germany, Indonesia, New Zealand and the Philippines also died in the attack.