Czech police said on Thursday they found explosives at the Palestinian mission in Prague while investigating a New Year's Day blast that killed the ambassador.
Ambassador Jamal al-Jamal died after opening a safe, police reported at the time. They ruled out an attack on the diplomat and said they believed he had mishandled an unknown explosive.
The Palestinian government has apologised for the incident which strained relations with the Czech Republic.
"I can confirm that some explosives have been found, which policeexperts are now examining," said Prague police spokesman Tomas Hulan.
A spokesman for the Palestinian embassy said he had no information on the discovery.
Earlier, police said their search had uncovered 12 handguns and assault rifles in the building.
Palestinian officials have said they received those firearms from communist Czechoslovakia more than 30 years ago.
Prague then had close relationship with the Palestine Liberation Organization (PLO), training its operatives and frequently hosting its leader, the late Yasser Arafat.
Embassies and diplomatic residences are normally protected from searches by host countries. But Czech police were able to search the Palestinian mission and residence because it was a brand new compound still without the official status.
Iraq's embassy in Prague handed over a rocket-propelled grenade and other weapons to authorities after the fall of Saddam Hussein.