Czech authorities are working to identify the explosive that killed the Palestinian ambassador, what caused the substance to explode and why it was being kept in an embassy safe.

Ambassador Jamal al-Jamal, 56 died Wednesday of massive injuries from the blast.

Pavel Kolar, the head of Prague's Institute of Criminology, said Thursday that the investigation could take several days.

Meanwhile, Palestinian Embassy spokesman Nabil El-Fahel told Czech radio the safe had been in regular use, contradicting Palestinian Foreign Minister Riad Malki's claim that the safe had been untouched for more than two decades.

The embassy recently moved to a new complex, and the safe was in the ambassador's residence.

Czech police say nothing has been found to suggest the diplomat had been a victim of a crime.