The security officials told Algerian media it wasn't clear whether the newly found bodies were those of hostages or of militants who stormed the facility last week, The Washington Post reported.
The death toll also includes a Romanian hostage who died of his injuries after escaping, the newspaper said.
Algerian officials Saturday confirmed the deaths of 23 other hostages and 32 militants.
An audiotape aired Sunday, a day after the four-day hostage crisis came to a bloody end suggests terrorists planned to bomb the gas plant, Algerian media said.
Algeria's Ennahar TV said the audiotape is of the al-Qaida-linked terrorist group at the In Amenas BP gas facility in the Sahara saying they would destroy the facility and "slaughter" U.S. hostages unless 100 imprisoned "comrades" were released, ABC News reported.
The recordings were made before the hostage crisis ended in a raid Saturday in which almost all the terrorists were killed, ABC News said.
The terrorists' audiotape included speakers claiming the hostages had been forced to wear bombs.
"The Americans that are here, we will kill them. We will slaughter them," Abdel Rahman el-Nigeri said in Arabic. Rahman el-Nigeri is a leader of the terrorists who held the facility and demanded the release of 100 "comrades" who were arrested 15 years ago.
He said some hostages were still alive after the Algerian military's first assault, but said the terrorists would bomb the army if it again got too close.
Hundreds of people had been held hostage in the gas plant before Saturday's raid. Citing military sources, Algerian state news said at least 685 Algerian workers and 107 foreign nationals were released during the siege.
Hostages from the United States, Japan, Norway, France and Britain are among the dead or unaccounted for.
A security official at the gas facility said many of the bodies found Sunday were so badly disfigured they could not be identified immediately.
"The bodies could be either Algerian or foreign hostages," the official was quoted as saying by USA Today.
The hostage-takers, identified as Islamic militants, stormed the plant last week in apparent retaliation for France's intervention in neighboring Mali. The attackers claimed to be from a group called Signers in Blood and said they were convinced Algeria would assist the French in their Mali campaign, The New York Times reported.
At least one American was among the dead. The Post said Obama administration officials and congressional staff members said Sunday they received little information from Algeria's government and military.