In this image made from video, a group of people believed to be hostages kneel in the sand with their hands in the air at an unknown location in Algeria. Algerian de-mining teams were scouring a gas refinery on Sunday, Jan. 20, 2013 that was the scene of a bloody four-day standoff, searching for explosive traps left by the Islamist militants who took dozens of foreigners hostage. The siege left at least 23 captives dead, and the American government warned that there were credible threats of more kidnapping attempts on Westerners. (AP Photo/Ennahar TV) ALGERIA OUT, TV OUTThe Associated Press
In this image made from video, a group of people believed to be hostages kneel in the sand with their hands in the air at an unknown location in Algeria. An Algerian security official says de-mining squads searching for explosives found "numerous" bodies Sunday, Jan. 20, 2013 at a gas refinery where Islamic militants took dozens of foreign workers hostage. (AP Photo/Ennahar TV) ALGERIA OUT, TV OUTThe Associated Press
Norway's Prime Minister Jens Stoltenberg is embraced by Executive Vice President in Statoil, Margrethe Oevrum, Saturday Jan. 19, 2013, after his visit at the drop-in center in Bergen for relatives of the Statoil-employees taken hostage in Algeria. In a bloody finale on Saturday, Algerian special forces stormed a natural gas complex in the Sahara desert to end a four-day standoff with Islamic extremists that left at least 19 hostages and 29 militants dead. With few details emerging from the remote site, it was unclear whether anyone was rescued in the final operation. (AP Photo / Anette Karlsen, NTB scanpix) NORWAY OUTThe Associated Press
In this undated image made from video, a man looks out from a bus towards what appears to be smoke rising in the horizon at an unknown location in Algeria. An Algerian security official says de-mining squads searching for explosives found "numerous" bodies Sunday, Jan. 20, 2013 at a gas refinery where Islamic militants took dozens of foreign workers hostage. (AP Photo/Ennahar TV) ALGERIA OUT, TV OUTThe Associated Press
Overseas Filipinos who were working at the sprawling oil field in Algeria which was attacked by terrorists, flash the "V" sign as they queue up at the Philippine Immigration upon arrival Sunday, Jan. 20, 2013 at the Ninoy Aquino International Airport in Manila, Philippines. The Department of Foreign Affairs in their statement, said that 39 Filipino workers, out of the 52 accounted for following the Algerian hostage crisis, arrived after being evacuated from Algeria via Palma de Mallorca in Spain. The workers claimed they were hundreds of kilometers away from the hostage-taking site but ordered evacuated. (AP Photo/Bullit Marquez)The Associated Press
ALGIERS, Algeria – Algerian bomb squads searched a gas refinery laced with mines on Monday, looking for more explosive traps a day after the discovery of more bodies throughout the site raised the toll from the terrorist siege well past 80.
Special forces from the Algerian military stormed the plant on Saturday to end the four-day siege, then the government began the painstaking work of finding and defusing the explosives planted in what government officials said was a plot by the Islamic extremists to blow up the complex and kill all their captives.
In a statement, the Masked Brigade, the group that claimed to have masterminded the takeover, warned of more such attacks against any country backing France's military intervention in neighboring Mali, where the French are trying to stop an advance by Islamic extremists.
"We stress to our Muslim brothers the necessity to stay away from all the Western companies and complexes for their own safety, and especially the French ones," the statement said.
Algeria said after Saturday's assault by government forces that at least 32 extremists and 23 hostages were killed. On Sunday, the Algerian bomb squads found 25 more bodies, said a security official, who spoke on condition of anonymity because of the sensitivity of the situation.
"These bodies are difficult to identify. They could be the bodies of foreign hostages or Algerians or terrorists," the official said.
In addition, a wounded Romanian who had been evacuated died, raising the overall death toll to at least 81.
Two private Algerian TV stations and an online news site said security forces scouring the plant found five militants hiding out on Sunday and learned that three others had fled. That information could not be immediately confirmed by security officials.
"Now, of course, people will ask questions about the Algerian response to these events, but I would just say that the responsibility for these deaths lies squarely with the terrorists who launched a vicious and cowardly attack," British Prime Minister David Cameron said. Three Britons were killed and another three were feared dead.
On Monday, Philippine Foreign Affairs officials said six Filipinos were among the hostages killed. Spokesman Raul Hernandez told reporters that 16 Filipinos have been accounted for and four others are still missing.
The dead hostages were also known to include at least one American and a French worker. Nearly two dozen foreigners by some estimates were unaccounted for.
It was unclear whether anyone was rescued in the final assault on the complex, which is run by the Algerian state oil company along with BP and Norway's Statoil.
Authorities said the bloody takeover was carried out Wednesday by 32 men from six countries, under the command from afar of the one-eyed Algerian bandit Moktar Belmoktar, founder of the Masked Brigade, based in Mali. The attacking force called itself "Those Who Sign in Blood" and has claimed to have Canadians in the cell as well.
The Masked Brigade said Sunday the attack was payback against Algeria for allowing over-flights of French aircraft headed to Mali and for closing its long border with Mali. In an earlier communication, the Brigade claimed to have carried out the attack in the name of al-Qaida.
Armed with heavy machine guns, rocket launchers, missiles and grenades, the militants singled out foreign workers at the plant, killing some of them on the spot and attaching explosive belts to others.
Algeria's tough and uncompromising response to the crisis was typical of its take-no-prisoners approach in confronting terrorists, favoring military action over negotiation. Algerian military forces, backed by attack helicopters, launched two assaults on the plant, the first one on Thursday.
The militants had "decided to succeed in the operation as planned, to blow up the gas complex and kill all the hostages," Algerian Communications Minister Mohamed Said told state radio.
Norwegian Foreign Minister Espen Barth Eide said the terrorists had tried to blow up the plant on Saturday but managed only to start a small fire. "That's when they started to execute hostages, and the special forces intervened," Eide said. Norway's Statoil said five Norwegians were still missing.
An audio recording of Algerian security forces speaking with the head of the kidnappers, Abdel Rahman al-Nigiri, on the second day of the drama indicated the hostage-takers were trying to organize a prisoner swap.
"You see our demands are so easy, so easy if you want to negotiate with us," al-Nigiri said in the recording broadcast by Algerian television. "We want the prisoners you have, the comrades who were arrested and imprisoned 15 years ago. We want 100 of them."
The Algerians' use of forced raised an international outcry from some countries worried about their citizens.
But French Foreign Minister Laurent Fabius said Sunday on French television: "The terrorists ... they're the ones to blame."
David Plouffe, a senior adviser to President Barack Obama, said that al-Qaida and al-Qaida-affiliated groups remain a threat in North Africa and other parts of the world, and that the U.S. is determined to help other countries destroy those networks.
Speaking on "Fox News Sunday," Plouffe said the tragedy in Algeria shows once again "that all across the globe countries are threatened by terrorists who will use civilians to try and advance their twisted and sick agenda."
Ganley reported from Paris. Associated Press writers Paul Schemm in Rabat, Morocco, and Lori Hinnant in Paris also contributed to this report.