Construction company owner Viktor Grebnov said human bones were first found at the road-building project in eastern Russian late last fall and work to remove them will resume this spring, RIA Novosti reported Monday.
"Construction at the site has stopped," the Russian news agency quoted Grebnov as saying. "The uncovered remains have been transferred to special containers. Now we are waiting for the earth to thaw so the remaining fragments can be carefully removed from the ground."
A company spokesman said the scale of the grave site, where witnesses said skulls and bones could be seen on the ground, was hard to determine and would be left to experts to investigate.
The site is not far from a memorial to victims of Josef Stalin's Communist regime from 1941 to 1953 and a local historian noted there had been a barracks for political prisoners a few miles away.
Millions of people were executed in political purges during Stalin's reign.