Fresh tremors and continuing eruptions have forced rescue workers off Mount Ontake in central Japan.
A plan to retrieve at least 24 dead bodies had to be abandoned after more choking ash and toxic gases spewed from the volcano’s flanks.
The activity is worrying seismologists that another major eruption could take place, and some rescue workers had to take shelter in lodges before reaching the safety of lower ground.
Two of the rescue helicopters have been grounded and there are still parts of the mountain that have not been reached since it blew its top last Saturday. Close to the crater ash covers the ground half a metre deep.
The official death toll stands at 36, but only 12 bodies have been able to be recovered so far, such is the challenge of working in such hostile conditions. The authorities had planned to deploy 800 searchers on Tuesday, triple the number of previous days, but the risk of eruption put paid to that.