SSP has announced up to 5,000 redundancies as part of "rapid and decisive action" to rebuild the business and recover after the pandemic.
The food and travel caterer, which operates 2,800 cafés, bars and restaurants in airports, train stations and other leisure locations, said it had been affected by the "total shutdown of the travel market" during the global lockdown.
The group confirmed that Covid-19 continued to have "an unprecedented impact" on the business and anticipated that only 20% of its units in the UK will have opened by autumn.
SSP Group chief executive Simon Smith said the group was now starting a "collective consultation" on a proposed reorganisation.
He said: "If the pace of the recovery continues at the current level, this could lead to up to around 5,000 roles becoming redundant from within the head office and UK operations.
"We are beginning to see early signs of recovery in some parts of the world and are starting to open units as passenger demand picks up. However, in the UK, the pace of the recovery continues to be slow. In response to this, we are now taking further action to protect the business and create the right base from which to rebuild our operations."
He said that with social distancing measures remaining in place, the recovery in passenger numbers in the rail sector was expected "to be prolonged" but added that the medium-term prospects for the group remained "positive".
As well as implementing job cuts, the group said its units in travel hubs would remain temporarily closed, and that salary reductions were in place across senior management, the executive committee and the board.
At the beginning of June the company released its interim results for the six months ended 31 March 2020 with like-for-like sales down 8.4%.
The company was later reported to have invited shareholders to reinvest their 2019 final dividend payment into new SSP shares to retain cash in the business.