"It could be as high as 20 [dead]," Claude Hogan, a spokesman for the British territory's government said on Monday night. He spoke as new flows of extremely hot rocks and gases from the Soufriere Hills volcano, located in the southern part of the island, set more houses on fire. Deadly pyroclastic flows - fast-moving bursts of 500 Celsius volcanic material - devastated seven villages in southern Montserrat last Wednesday.
Mr Hogan said nine or 10 bodies had been recovered and officials were fairly confident another 10 people had been killed, though their bodies had not yet been found, in the village of Farm's, which was razed almost to the ground in the disaster.
"That village we know is all but consumed except for a few houses on the steeper side of the valley. The village is gone. Those 10 people were in there, we know," he said.
Mr Hogan said another 24 people were still considered missing.
Rock and ash surged down the volcano's south-western flanks at mid-afternoon on Monday, sending a dark cloud into the sky that obliterated the sun, and roaring through evacuated villages near Plymouth, Montserrat's capital. There were no reports of additional injuries.
Baroness Liz Symons, under-secretary of state with responsibility for the Caribbean, visited Montserrat on Sunday and Monday and reiterated the British government's commitment to giving financial support to the tiny island and to developing its northern third, which is considered safe.