MOSCOW/KIEV, July 28 (Xinhua) -- The investigation into the crash of Malaysia Airlines flight MH17 should be held under the aegis of the United Nations, Russian Foreign Minister Sergei Lavrov said on Monday.

"We believe that such an inquiry must begin as quickly as possible under the UN aegis," Lavrov told reporters.

"We are alarmed about the fact that some of our partners are trying to turn the practical, all-involved investigation into separate bilateral talks with the Ukrainian government," he said.

He added that Russia demands the implementation of a safe access for international investigators, saying his country hopes that no one will try to cover up traces during the investigation.

"We insist on an impartial and transparent investigation into the crash. Russia abides by the UN Security Council resolution, which requires all parties not to take any action that might complicate the investigation," Lavrov said.

Russia will seek a ceasefire for the investigation and the West should influence Kiev in this regard, he said.

"We heard about Ukrainian President Petro Poroshenko's pledges. But his words do not match his deeds. The fighting continues," he said.

Lavrov and U.S. Secretary of State John Kerry on Sunday called for an immediate ceasefire in eastern Ukraine, but the two sides kept blaming each other for hindering the investigation and escalating conflict between government forces and insurgents.

Meanwhile, Ukrainian authorities said a team of international investigators, who examined the content of the Malaysian jetliner's black boxes, pointed to a "massive explosive decompression" as a possible cause of the disaster.

According to a report, published on the website of the Donetsk Regional State Administration, the crash of MH17 was probably caused by "a massive explosive decompression due to multiple shrapnel injuries from a rocket explosion."