Hamas' October 7 attack at the Nova Music Festival was raised from 260 to 350, with officials stressing the number could rise more as new information surfaces.
The increase was based on data from Israel's National Insurance Institute, which found that the number of victims who were shot and then burned in their cars while attempting to flee is higher than previously thought.
Another 40 attendees of the all-night rave were taken to Gaza as hostages.
Some 1,200 people were killed during Hamas' October 7 attack on Jewish communities near the Gaza Strip and around 240 people are confirmed to be held hostage in Gaza. Authorities have identified 870 of the victims, while others still remain unaccounted for.
Archaeologists have been enlisted to help find the remains of massacred Israelis while search teams continue looking for bodies in open areas.