A record 314,000 redundancies were recorded in the three months to September as the coronavirus took a further toll on jobs.
Figures from the Office for National Statistics (ONS) also showed the unemployment rate rose to 4.8%, its highest level since November 2016 and up from 4.5% the month before.
Some economists said employers cut roles in anticipation of the furlough scheme – which has just been extended by the chancellor – being phased out by the end of October.
ONS data for October suggested that the number of employees on UK payrolls has fallen by 782,000 since March.
The total number of people officially classed as unemployed rose by 243,000 to 1.62 million in the three months ending in September, the biggest increase since 2009.
The ONS jobs data pointing to strong growth in redundancies in the first two weeks of September.
That took its heaviest toll on those aged 16-24 – with the group seeing redundancy rates more than double compared to the same period a year ago.
Responding to the latest jobless numbers, Mr Sunak said: “Today’s figures underline the scale of the challenge we’re facing.
“I know that this is a tough time for those who have sadly already lost their jobs, and I want to reassure anyone that is worried about the coming winter months that we will continue to support those affected and protect the lives and livelihoods of people across this country.”
