NatWest has set aside a further £2.1bn to cover potential bad debts caused by the coronavirus crisis.
It means the rebranded bank, formerly the Royal Bank of Scotland, reported a pre-tax loss of £770m for the first half of this year.
This is a swing from a £2.7bn profit in the same period a year earlier.
The results are the first since the group changed its name last week.
Chief executive Alison Rose said: “Our performance in the first half of the year has been significantly impacted by the challenges and uncertainty our economy continues to face as a result of Covid-19.
“However, NatWest Group has a robust capital position, underpinned by a resilient, capital-generative and well-diversified business.”
NatWest expects to set aside between £3.5bn and £4.5bn for the whole of 2020 to deal with the economic fallout of the pandemic.
Ms Rose added: “Throughout this crisis we have provided exceptional levels of support to our customers, colleagues and the communities we serve. I am proud that our colleagues have consistently shown they are putting our purpose at the heart of everything they do.
“Through our strong balance sheet and prudent approach to risk, we are well placed not only to withstand Covid-19-related impacts but also to provide the right support to those who will need it most in the tough times to come.”
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