Vitaly Churkin said Ukrainian forces were targeting civilians in the area and failing to abide by the resolution that calls on all sides to refrain from fighting near the crash site.
"Ukrainian security officials have said that it was their intention to take over the site militarily," Churkin told a news conference at UN headquarters in New York.
"That of course would amount to a direct violation of Resolution 2166."
The Security Council last week adopted the Australian-backed resolution condemning the downing of the passenger plane that left 298 dead, demanding that all military operations cease and calling for a full investigation.
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After explosions and fighting blocked a new attempt by Dutch and Australian police to access the east Ukraine crash site, Kiev confirmed today that its forces were engaged in fierce clashes with rebels nearby.
The Ukrainian military said its troops had battled their way into a string of towns around the scene, including Shakhtarsk, 10 kilometers (six miles) away.
Churkin said Kiev's offensive "has exceeded all humanly imaginable limits" with shelling of cities and towns. "Civilians are dying by the dozens," he said.