Martin Sousek said the safe was under constant supervision as it was moved into the new residence of Palestinian ambassador Jamal al Jamal and that Jamal was present the entire time, the Czech news agency CTK reported Monday.
Jamal was fatally injured New Year's Day a short time after the safe was delivered. His daughter alleged her father was murdered by someone who put an explosive device in the safe during the time it was being moved.
Sousek rejected the allegation.
"The safe was being constantly watched," he said. "It was closed all the time."
Sousek said people from the Palestinian embassy decided where the safe should be placed in the house.
Czech police have discounted Jamal's death as murder. They are investigating whether the blast was caused by negligence. They believe Jamal may have been mishandling the device when it detonated.
Police said they found 12 unregistered firearms in the embassy building.