ALGIERS — The prime minister of Algeria offered an unapologetic defense Monday of the country’s tough actions to end the Sahara hostage crisis, saying the militants who had carried out the kidnappings intended to kill all captives and the army saved many from death by attacking.

But the assertion came as the death toll of foreign hostages rose sharply, to 37, and as US officials said they had offered sophisticated surveillance help that could minimize casualties, both before and during the military operation to retake a seized gas field complex in the Algerian desert.