Revelations of radioactive cow carcasses buried beneath land slated for a $20 billion education precinct in Melbourne's west should be no cause for alarm, the state government says.

Fairfax Media revealed on Sunday 60 carcasses were buried at a Werribee site the government was trying to sell to a Chinese consortium

A cow near the site in Werribee where radioactive carcasses are buried. Credit:Joe Armao

Documents obtained by Fairfax Media estimated the cost of cleaning up the radioactive waste could reach $300 million.

Environment Minister Lily D'Ambrosio did not deny the 775-hectare site was contaminated by toxic waste.