Citi analysts said the huge surge would be driven by even higher energy costs after gas prices rose 25% last week and electricity was up 7%.

The bank is now expecting the energy price cap to be set at £3,717 in October, up from £1,971 today, before jumping to £4,567 in January and then £5,816 in April.

Benjamin Nabarro, chief UK economist at Citi, said: “Our latest estimate, updated for the further 25% and 7% rally in UK gas and electricity prices last week, points to a further upside shift in UK inflation.

“Accounting for these developments, as well as updating our own weights for CPI/ RPI and honing our own accounting for curve backwardation, we now expect CPI inflation to peak at over 18% in January. RPI inflation, we think, will peak at over 20%.”

If accurate, the predictions mean that by April next year energy bills will swallow almost a fifth of the average household’s income, which was £31,400 in 2021 according to the Office for National Statistics.

Inflation is already running at 10.1%, ONS figures for July show. The Bank of England has warned it now expects this to rise to 13% this autumn when energy bills go up.

This could be revised up again, however, as Russian president Vladimir Putin continues to restrict gas supplies, relentlessly pushing up prices.

It will heap even more pressure on households’ finances, which are already stretched. A cost of living “tracker” from money management app HyperJar suggested a typical British family had seen their disposable income drop by £145 a month.

ONS figures revealed average pay plummeted at the highest rate since 1977 between April and June, with regular weekly wages falling by a record 3% in real terms.