Footage from the southern city of Volgograd showed a fresh landslide on an embankment near the stadium, which made a several-metre-deep hole in it and fully covered a sidewalk with mud.
A spokesman for the state Sport In company overseeing the construction said there were also leaks inside the stadium which could take up to a week to repair.
Volgograd Arena, a stadium that can accommodate up to 45,000 spectators, was built for the World Cup at a cost over 16 billion roubles ($257 million), according to data on the regional government's website.
"This happens once in a hundred years," a Sport In spokesman said.
The Stroytransgaz company, which built the stadium, gave no immediate comments.
($1 = 62.2500 roubles)
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