U.S. Secretary of State John Kerry says separatists in eastern Ukraine used a surface-to-air missile from Russia to shoot down a Malaysia Airlines plane on July 17.
"It's pretty clear that this is a system that was transferred from Russia into the hands of separatists," said Kerry on CNN's "State Of The Union" program on July 20.
He added that the United States knew "with confidence" that the Ukrainian government did not have a Buk missile launcher in the vicinity of the attack, which killed 298 all people on board.
Meanwhile, the self-proclaimed leader of a separatist region in eastern Ukraine said the so-called black boxes from downed Malaysia Airlines Flight MH17 had been found and will be given to the International Civil Aviation Organization.
Aleksandr Borodai, the self-styled prime minister of the self-proclaimed "Donetsk People's Republic," said at a press conference in Donetsk on July 20 that pro-Russian separatists had what appeared to be the black boxes from the airliner, which crashed on July 17.
Borodai said rebel forces had recovered "some items, presumably the black boxes," and said they were delivered to the eastern city of Donetsk, which is controlled by the separatists.
Different separatist leaders have claimed at various times in the past three days to have had one or both of the black boxes and later denied having either of them.
WATCH: Emergency workers seemingly find a "black box" from Malaysia Airlines Flight MH17 (natural sound).
Separatist forces control the area -- near the town of Torez, close to the Russian border -- where the airliner and 298 people onboard crashed.
Officials say 223 bodies of the people aboard the downed airliner have been taken from the fields in eastern Ukraine where they had been lying since the crash.
Some reports said it was unclear where the bodies had been taken but the Reuters news agency said railway workers claimed at least some of the bodies had been taken to refrigeration wagons at the train station in Torez, some 15 kilometers from the crash site.
Ukrainian emergency services spokeswoman Nataliya Bystro said government workers and rebels had gathered the bodies but she added that the rebels then took the bodies to an unknown location.
Russian TV channel Rossia-24 reported that the bodies had been taken to the morgue in the city of Donetsk.
There were also reports that "Donetsk People's Republic" self-styled deputy prime minister, Andrei Purgin, has given a guarantee of safety to international experts to visit the site of the crash if Kyiv agrees to a truce.
A monitoring team from the Organization for Security and Cooperation in Europe (OSCE) has been able to visit the site briefly each of the last three days but members of the OSCE team said separatist fighters treated the monitors rudely and did not allow them full access to the crash scene.
Ukrainian Security Council spokesman Andriy Lysenko told a July 20 news conference that pro-Russian separatists were "doing everything to hide the evidence of the involvement of Russian missiles in the shooting down of that airliner."
Lysenko also claimed Russia is continuing to supply the separatists with "heavy weaponry."
In the Netherlands, where the ill-fated Malaysian airliner departed the day it was shot down, church services called for prayers for those killed and their relatives.
Most of the passengers aboard the plane, at least 193, were Dutch citizens.
The chairman of the Dutch Bishops Conference, Cardinal Wim Eijk, called on worshippers to "pray for strength and courage for the relatives" of those lost in the plane tragedy.
Dutch Prime Minister Mark Rutte has expressed outrage at reports that the bodies of at least some of those killed when the Malaysian airliner was shot down have been rifled by looters and that attempts have been made to use credit cards belonging to the deceased.
Rutte has made several phone calls to Russian President Vladimir Putin expressing his disgust at the situation at the crash scene and calling on Putin to use his influence to convince the separatists in eastern Ukraine to cooperate with international recovery efforts and an investigation.
Outrage has been growing at the delay in allowing representatives of Malaysia Airlines, international air safety experts ,and others to access the site and properly retrieve the bodies of the deceased and conduct an investigation into the causes of the crash.
Australia's Prime Minister Tony Abbot criticized the situation at the crash scene as being "absolutely chaotic."
More than 30 Australian citizens and permanent residents were aboard the Malaysian airliner.
At a church service Abbot attended, Auxiliary Bishop of Sydney Peter Comensoli called the tragedy "the outcome of a trail of human evil."
The office of French President Francois Hollande released a statement on July 20 saying Hollande had spoken with German Chancellor Angela Merkel and British Prime Minister David Cameron.
The statement said the three agreed "to demand from Mr. Putin today that he ensure that Ukrainian separatists allow emergency workers and investigators free and complete access" to the site where the airliner crashed after being shot down.
The statement also said that if Russia "does not immediately take the necessary measures, consequences will be drawn by the European Union at the Foreign Affairs Council which takes place" on July 22.