The oil and gas company had informed the Pakistan Nuclear Regulatory Authority (PNRA) about the properly waxed and sealed containers measuring 0.9 by 1.2 metres on July 2.
"The material found contained only two sealed radioactive sources in a very small quantity having very low radioactivity," the PNRA said in a statement on Friday.
The nuclear watchdog said the large size of the casing was due to heavy shielding around the radioactive material.
According to the Dawn newspaper, which first reported the discovery, the containers had earlier been categorized as "orphan radioactive sources" because the OGDCL had no record of the material, which is suspected of being of Soviet origin.
The site where the containers were unearthed was used by a Soviet oil exploration company until the late 1960s when the firm wrapped up its operations in Pakistan.
"These radioactive sources are used in oil and gas exploration," the PNRA statement said.
Nuclear experts believed that no one had been exposed to radioactivity as the material lay buried and the site was not accessible to the public.
The area is being surveyed to locate any other such containers.

Copyright dpa (Deutsche Presse-Agentur Gmbh), 2008