KUALA LUMPUR, July 21 -- Malaysia has announced the establishment of a joint investigation team on the MH17 incident, which comprises officials from the Netherlands, Malaysia, Britain and the United States.

However, the Ukrainian government had informed the investigation team that the crash site was under the full control of separatist groups and "it cannot guarantee the safety of the international team in and around the crash site," Malaysia's Transport Minister Liow Tiong Lai said in a statement in Kiev on Sunday.

The situation was further hampered by reports that a number of competing separatist groups control the area in and around the crash site, with no clear leader or chain of command, he said.

Malaysia was deeply concerned about this situation and demanded immediate and unrestricted access to the crash site and safety guarantee for international investigators and search and recovery personnel.

The Malaysia Airliners MH17 flight with 298 people on board crashed Thursday in eastern Ukraine, with no survivors found so far, making one of the worst tragedies in the history of civil aviation.

"Malaysia demands that all human remains must be allowed to be recovered, identified and repatriated," the minister said in Kiev.

So far, the only international body that has managed to briefly access to the crash site is the Organization for Security and Cooperation in Europe, he said.

Liow arrived in Kiev on Sunday, accompanied by the director- general of the Malaysian Department of Civil Aviation and the chairman of Malaysia Airlines.

He has met with Ukrainian Deputy Prime Minister Volodymyr Groysman, chair of the Ukrainian Special Government Commission on MH17, as well as Ukrainian Minister of Infrastructure Maksym Burbak and Chairman of the Ukrainian State Aviation Administration Denys Antonyuk.

A Malaysian team of 133 officials and experts, comprising search and recovery personnel, forensics experts, technical and medical experts arrived in Kiev Saturday morning.