The Palestinian ambassador to Prague was killed in an explosion that was triggered when he opened the door to a safe, Czech police said.
Jamal al-Jamal, 56, died in hospital after the incident at his home this morning.
"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 – whic hmay 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 Mr Jamal opened a safe that had come from the embassy's old offices.
The mission is in the course of moving into new premises next to the residence in a suburb of the capital.
Ms Zoulova told reporters: "The possibilities include inexpert handling of an explosive device or its spontaneous detonation... The device was in a safe and was triggered after the door of the safe was opened."
Some safes can be fitted with small charges to destroy secret documents in the event of the lock being tampered with.
A spokesman for the embassy, Nabil el-Fahel, said he had no details on what it was that blew up. "We need to wait for the results of the police investigation," he said.
Mr Jamal suffered lethal injuries to his head, chest and abdomen, surgeon Daniel Langer told Czech television.
No one else was injured in the explosion, police said, although a spokeswoman for Prague's emergency medical services said a 52-year-old woman was treated for smoke inhalation and shock.
Mr Jamal's family was at home at the time of the blast.
No sign of damage to the two-storey house was visible outside, but police cordoned off part of the street while bomb experts searched the premises.
The Palestinian foreign ministry said it would send a team to Prague to help with the investigation.
Palestinian Foreign Minister Riyad al-Malki, quoted by WAFA, said Mr Jamal was "martyred in the line of duty".
Born in Beirut to a refugee family, Mr Jamal joined Yasser Arafat's Fatah faction of the Palestine Liberation Organisation in 1975 and served in PLO missions to Bulgaria and Czechoslovakia in the 1980s.
Part of the diplomatic corps of the Palestinian Authority that governs the West Bank under interim peace accords with Israel, he had been its consul in Alexandria since 2005.
He took up the ambassador post to Prague only last October.