Opposition politicians in Guatemala want the head of the emergency response agency (Conred) to be dismissed.
They say Conred failed to heed advance warnings about the deadly eruption of the Fuego volcano.
A senior opposition figure, Mario Taracena, said the government should investigate whether there was criminal negligence.
Ninety-nine people are now known to have died since Sunday, and many others remain unaccounted for.
Villages on the slopes were buried in volcanic ash and mud after Fuego erupted.
Subsequent smaller eruptions and the high temperatures of the rock and mud debris have made search teams' work extremely difficult.
More than 1.7 million people have been affected by Sunday's eruption, with more than 3,000 evacuated.