The boss of energy regulator Ofgem said that householders should expect a rise in energy bills in England, Wales and Scotland in October.
He said that not being able to afford energy bills was a matter of life and death for some people.
The market is highly volatile and we do expect further price increases later this year, he said.
He said that I talk to customers on a regular basis, and I know how tough rising energy prices are for many households and businesses.
He pointed out a case in which a woman who was being treated for a brain tumour had worries about keeping up with energy bills.
He said that it was shocking to learn that she feels more comfortable in hospital where she can eat and be warm than at home.
A widely-predicted increase in October comes after a 700 typical rise in annual domestic gas and electricity bills, which took effect in April when the price cap was last raised. Consumers in Northern Ireland - not covered by the price cap - have already seen significant increases in bills.
The National Institute of Economic and Social Research said 1.5 million households in the UK will struggle to pay food and energy bills over the next year.
A Treasury spokeswoman said the country had had a strong economic recovery from the Pandemic but acknowledged that these were anxious times and that the government was taking action to support households.