Czech police say the weapons and explosives discovered at the Palestinian Embassy in Prague where a possibly booby-trapped safe killed the ambassador were decades old.

In a Thursday statement, they say that ballistic and other tests showed that 12 illegal weapons and explosives found following the explosion that killed Ambassador Jamal al-Jamal on Jan. 1 date back to the 1970s and 80s.

Palestinians authorities previously have said the weapons were given to them decades ago as gifts by officials in Czechoslovakia during the Cold War when it was a communist country with close ties to the Palestinian Liberation Organization.

It remains unclear what caused the safe to explode. The ambassador's death is being investigated as a case of negligence.