The UK public’s appetite for eating out has plunged to its weakest since the spring amid growing evidence of the impact of the Omicron variant on the hospitality sector during its crucial pre-Christmas period.

The number of seated diners fell by 14 percentage points in the week ending 20 December to 88% of the level in the same period of 2019, before the start of the pandemic, according to the weekly digest of flash economic indicators from the Office for National Statistics (ONS).

Using data from the online restaurant booking site OpenTable and other sources, the ONS said Britons were eating out less and working from home more in response to rising infection rates and the government’s plan B measures.

Amid widespread reports of bookings being cancelled, the drop in the number of diners in the latest week was the sharpest since early September and the lowest level since restaurants reopened indoors in England, Scotland and Wales in May after last winter’s lockdown. It was also the first time the weekly comparison with 2019 has dropped below 100% since May.

Restaurants in London have been especially hard hit by Omicron, with the number of diners in the latest week falling 18 points to 57% of the level in the same period of 2019. In Manchester, despite an eight-point drop on the week, the number of diners stood at 104% of the level in the run-up to Christmas 2019.

The ONS said the number of firms reporting staff working from home in the latest two weeks had risen by two points to 14%, with a marked impact on businesses reliant on consumers.

Transactions at Pret a Manger sandwich outlets were lower in the week ending 16 December than in January 2020 in six of seven urban locations, with London again the most affected city. While trade in regional towns remained above pre-pandemic levels, sales in the capital dropped by 29 points to barely 50% of the January 2020 level.

The ONS report showed retailers doing less badly than restaurants, with footfall in the latest week 81% of its 2019 level – a drop of only one percentage point. Credit and debt card payment purchases were up 4% on a year ago.

Earlier this week, the chancellor, Rishi Sunak, announced an emergency £1bn package to help businesses struggling with the impact of Omicron.

Meanwhile, analysts are warning that the economy is likely to contract in December even if restrictions in England remain unchanged.

Andrew Goodwin, a UK economist at the consultancy firm Oxford Economics, said: “Though the government has opted to defer a decision on introducing further restrictions until after Christmas, it seems likely that a mix of greater consumer caution and reduced mobility will ensure that the UK’s GDP falls in December.”