Mount Ontake continued shaking violently and coughing out toxic steam, suspending efforts on Tuesday to retrieve victims believed to have been killed in the Sept 27 eruption at Japan's second-highest volcano.

The search for bodies buried in ash near the summit was called off for the day, said an official at Nagano prefecture's crisis management center, who didn't want to be named because he wasn't authorized to speak publicly. Crews with idled helicopters had been waiting since morning near the foot of the mountain in central Japan for volcanic activity to subside.

At least 36 people are believed to have died in the explosion, which left 69 others injured, 29 of them seriously, Japan's Fire and Disaster Management Agency said in a statement. An unknown number remain missing.