A team of international observers set to investigate the alleged downing of the Malaysian Airlines Flight MH17 over the sky in war-hit Eastern Ukraine, have been unable to reach the area where the airlines crashed, due to blockage, reports suggest.

The Organization for Security and Co-operation in Europe (OSCE) has said access to the site had been controlled by armed men, with one 'drunk' man reported to be firing shots into the air, while the bodies of those who died with the plane have been kept untouched in the area.

This comes after the United States government concluded on Friday that the passenger jet that crashed, was in fact, shot down by a Russian-made surface-to-air missile launched from rebel-held territory and the device was most likely provided by Russia to pro-Moscow separatists, the New York Times reports.

While American officials are still investigating and studying the chain of events that led to the ultimate mid-air explosion of the aircraft, they have cited various evidences that point fingers on Russian involvement, in one of the biggest aviation tragedy that killed 298 innocent people.

The jet, flying from Amsterdam to Kuala Lumpur, fell between Krasni Luch in Luhansk region and Shakhtarsk in the neighboring region of Donetsk.

Latest figures releaed by the Malaysian airliner show the plane was carrying, among others, 189 Dutch nationals, 27 Australians, 44 malaysians (including 15 crew members), 12 Indonesians and 10 Britons.

Michael Bochirkiw, a member of the OSCE team, was quoted by news sources as saying that their access had been limited, despite the regional rebel commander giving them assurances that their advances to the site won't be blocked.

"A visibly intoxicated armed guard fired his rifle in the air when one of the observers walked out of the prescribed area," Bociurkiw told reports.

Calling their behavior "impolite and unprofessional" the spokesman specifically mentioned that some gunmen in the area seemed intoxicated, while others would not let the 25-member team of observers, have a look at the wreckage of the Boeing 777.

"We had expected unfettered access, that's the way we work," he said. "Unfortunately the task was made very difficult. Upon arrival at the site...we encountered armed personnel who acted in a very impolite and unprofessional manner. Some of them even looked slightly intoxicated."

The bodies of the passengers had not been touched and lay as they fell – and the personal belongings of the dead passengers have been arranged in piles as if "for show", Bochirkiw added.