The stock market disclosure came after a report in today's Financial Times that the bank was set to announce a one-third fall in operating profits to £5.17 billion, alongside a trebling in bottom-line profits to £2.86 billion.
Barclays, which is due to present its results at 7am tomorrow, confirmed that the figures were set to be £5.2 billion and £2.9 billion respectively.
The FT forecast a slight drop in income to £27.9 billion, adding that the sharp rise in statutory profit reflected lower charges on the value of its own debt.
The underlying profit figure of £5.2 billion is slightly below the consensus forecast in the City for around £5.4 billion.
The drop in profits follows a year in which it added £2 billion to its bill for customer mis-selling scandals and was forced to ask shareholders for £5.8 billion in a rights issue after revealing a £12.8 billion hole in its finances.
Chief executive Antony Jenkins will give an update tomorrow on his Project Transform programme to overhaul the bank's culture and practices.
The review was launched in the wake of the bank's £290 million Libor-rigging fine and Mr Jenkins's appointment as successor to former boss Bob Diamond.
It has been reported that Barclays is planning to axe several hundred jobs at a senior level in its investment banking business as well as ordering staff to cut out all non-essential overseas travel to slash costs.
The group will also be pressed on branch closures, in spite of its denial of recent reports that up to a quarter of its 1,600 sites in the UK could close.
Tomorrow's results are expected to fuel anger over City bonuses after it was reported that Barclays plans to lift its total bonus pot to between £2.3 billion and £2.4 billion from £2.17 billion in 2012.
Mr Jenkins sought to head off some of the criticism when he waived a bonus for 2013 worth up to £2.75 million, after the bank faced "very significant costs" over a series of scandals and carried out a cash-call on shareholders.