The international community is demanding that rebels controlling the remote area in eastern Ukraine where Malaysian Airlines Flight 17 was shot down on Thursday grant investigators and monitors full access to the site.

On a series of television interviews on Sunday, US Secretary of State John Kerry said the investigation had already been "seriously compromised."

Kerry spoke of "drunken separatists piling the remains of people into trucks in an unceremonious fashion," on CNN's State of the Union with Candy Crowley, while rebounding calls for Russia to place pressure on rebels, who have been restricting the movement of international monitors and journalists at the scene, to grant investigators safe and unhindered access to the site.

“We need full access," Kerry told Fox News Sunday. "This is a moment of truth for Russia.”

MH17 was en route from Amsterdam to Kuala Lumpur when it was reportedly shot down at an altitude of 30,000 feet by a surface-to-air missile over remote rebel-held battlefields in Ukraine near the Russian border. All 283 passengers and 15 crew on board were killed.

International outrage has followed accounts of the alleged mistreatment of the victims, who hail from 13 nations. A Ukrainian military official said Saturday that valuables including credit cards had been looted from some of the remains.

The UN Security Council is currently contemplating a draft resolution demanding that "armed groups in control of the crash site and the surrounding area refrain from any actions that may compromise the integrity of the crash site and immediately provide safe, secure, full and unfettered access to the site and surrounding area."

The draft resolution also "insists that the bodies of the victims are treated in a dignified, respectful and professional manner."

Pro-Russia separatists at the crash scene in eastern Ukraine announced on Sunday that they have retrieved the plane's black boxes and will turn them over to the International Civil Aviation Organization, although it was not specified when that would occur.

Alexander Borodai, Prime Minister of the self-proclaimed Donetsk People's Republic militia group, denied any evidence-tampering, despite accounts that rebels have been snatching plane fragments and carting away charred bodies and parts from the unsecured site.

At least 192 bodies are currently being held in refrigerated train cars at a station nine miles away in the rebel-held town of Torez, and "will go nowhere until experts arrive," Borodai told the Associated Press.

An additional 27 bodies had been recovered at the site on Sunday, Ukraine's Deputy Prime Minister Volodymyr Groysman confirmed.

The other victims remain unaccounted for, although Michael Bociurkiw, a spokesman for the Organization for Security and Cooperation in Europe, told reporters some may have been "vaporized" by intense heat and flames as the engines came down.

Ukrainian authorities and pro-Russia separatists continue to point the finger at each other, though both have shirked responsibility for the downing of the Boeing 777 jet.

The Ukrainian Security Service (USS) released over the weekend what it claims to be a series of intercepted calls between members of pro-Russia militia seemingly admitting to shooting down a civilian plane over the town of Hrabovo and suggesting Moscow's involvement in the search for the black boxes, or flight data recorders.

The US embassy in Kiev issued a statement on Sunday stating that, "Flight MH17 was likely downed by a SA-11 surface-to-air missile from separatist-controlled territory in eastern Ukraine."

The statement goes on to claim that less than five days before the crash, "Russia sent a convoy of military equipment with up to 150 vehicles, including tanks, armored personnel carriers, artillery, and multiple rocket launchers" to rebels in eastern Ukraine.

Moscow has denied any involvement.

Malaysian Transport Minister Liow Tion Lai expressed concern on Saturday that the wreckage site remains unsecured. He said, "the integrity of the site has been compromised, and there are indications that vital evidence has not been preserved in place."

Prayer services in Churches around the world have been held to pay tribute to crash victims, while in the Ukrainian town of Kharkov, about 185 miles north of the scene, ten hotels have offered free rooms for victims' relatives.

At a service held at the St. Vitus church in the Dutch city of Hilversum, Father Julius Dresme echoed the sentiments of his country, which lost 189 citizens in the crash:

"It's terrible, and everybody's hearts are bleeding and crying," he said.

Follow Liz Fields on Twitter: @lianzifields