The gambling group, which includes Mecca Bingo with sites across the Black Country and in Telford and Grosvenor Casinos with a casino at Walsall, reported a 76 per cent plunge in like-for-like net gaming revenues in its third quarter to the end of March, with online sales unable to offset the hit to its venues.
All of its UK sites were closed during the quarter, while it said nine Spanish venues were open at the end of March, albeit with very strict capacity restrictions.
It is set to reopen English sites on May 17 under the Government's road map plans to exit lockdown.
The firm said its third-quarter venue sales were almost wiped out, crashing 98 per cent, while digital sales dropped three per cent year on year.
Digital sales rose three per cent compared with the previous three months, and Rank said it expects online revenues will return to year-on-year growth in the first quarter of 2021-22 as it focuses on growing its digital operation.
Rank said Grosvenor casinos saw a two per cent fall in online revenues compared with the previous three months, while Mecca notched up a four per cent rise.
The group also gave assurances over the strength of its balance sheet despite the pandemic trading woes, confirming it ended the quarter with £89.8 million in cash and available financing facilities.
Rank chief executive John O'Reilly said: "Our business has inevitably been heavily impacted by the pandemic but, with the strong support and dedication of our colleagues, we are now very much looking forward to reopening our casino and bingo venues, welcoming back our customers and providing the great entertainment and omni-channel service in a Covid-safe environment we know they enjoy."
Rank warned in January that trading at its venues is not likely to fully recover until the middle of next year.
It made the gloomy prediction as half-year results showed it slumping to a £59.4 million pre-tax loss for the six months to December 31 against profits of £48.2 million a year ago due to the pandemic and restrictions.