Czech investigators have discovered explosives at the Palestinian embassy complex in Prague where a possibly booby-trapped safe killed the ambassador, police said Thursday.
Spokesman Tomas Hulan confirmed the discovery, saying that it was sent for testing at Prague's Institute of Criminology.
Police already had found 12 illegal weapons in a search following the explosion that killed Ambassador Jamal al-Jamal, a career diplomat who had only started his posting in October.
It remains unclear what caused the safe to explode but the ambassador's death is being investigated as a case of negligence while the found of the explosive and weapons are considered illegal arms possession.
The Palestinians have officially apologized for the incidents after the Czech Foreign Ministry demanded an explanation, accusing the Palestinians of breaching international obligations.
The ministry said Thursday it would not immediately comment on the explosive.
Police said Thursday they received a letter from the Palestinian authorities saying the weapons were given to them as gifts by the officials of the former communist Czechoslovakia.
Czechoslovakia was part of the Soviet bloc that had warm ties with the Palestinian Liberation Organization.
According to police, the Palestinians said the weapons were never used and always kept in a safe.
Police said experts are trying to determine whether the weapons were used in any criminal activity in the past. The ballistic testing might take weeks, police said.