There were close to 697,000 deaths in the UK in 2020 – nearly 91,000 more than would be expected based on the average in the previous five years.
The figure represents an increase of 15 per cent and make it the largest rise in excess deaths for more than 75 years.
Excess deaths are a measure of how many more people are dying than would be expected, based on the previous few years.
Any death involving Covid-19 in 2020 is counted as an excess death because the virus did not exist before then.
Separately, under a measure known as age-standardised mortality – when the age and size of the population is taken into account – 2020 saw the worst death rates since the 2000s.
King’s Fund chief executive Richard Murray told the BBC that the picture was likely to worsen, given Covid deaths were rising following the surge in infections over recent weeks.
Mr Murray said: “The UK has one of the highest rates of excess deaths in the world, with more excess deaths per million people than most other European countries or the US. It will take a public inquiry to determine exactly what went wrong, but mistakes have been made.
“In a pandemic, mistakes cost lives. Like many countries, the UK was poorly prepared for this type of pandemic.”
It came as the Office for National Statistics (ONS) found that there were 3,144 deaths registered in the week ending January 1 which mentioned Covid-19 on the death certificate.
It also found that of the 4,956 deaths registered which occurred in hospitals, 47.7 per cent involved coronavirus, up from 40.2 per cent the previous week.
And deaths involving Covid-19 in care homes accounted for more than a quarter (27.6 per cent) of all deaths in care homes registered during the seven-day period.