The Palestinian ambassador to Prague was killed in an explosion that was triggered when he opened the door to a safe, Czech police said.
"According to information from the investigation so far, this was definitely not a terrorist attack," national police president Martin Cervicek said on Czech Television.
Police spokeswoman Andrea Zoulova said an explosive - which may have been part of a security mechanism - went off after the safe was opened. "With the greatest probability, an explosive device placed on the door of the safe was triggered," she said.
The Palestinian foreign ministry, in a statement reported by the official WAFA news agency, said the blast happened minutes after Jamal opened a safe that had come from the embassy's old offices.
Some safes can be fitted with small charges to destroy secret documents in the event of the lock being tampered with.