British Airways expects its fuel costs to rise by £300m ($578m) during the next financial year from 1 April, due to the continuing high price of oil.
Like all airlines, BA continues to be hit by high oil prices
The comments were made by the airline's finance director John Rishton, who also forecast that annual revenues would rise between 3% and 4% in 2005/06.
In February BA blamed high fuel costs for a 40% drop in quarterly profits.
On Tuesday the airline said former boss of Aer Lingus, Willie Walsh, will be its next chief executive.
Worldwide airline pressures
Mr Walsh will take over when current chief executive Rod Eddington retires in September.
Mr Rishton reiterated that revenues for 2004/05 would increase by between 3% and 3.5%.
BA's shares closed 5.75 pence lower at 273.25 pence, following the news on Thursday.
In a separate announcement, Japan Airlines said on Thursday that it is to cut 1,400 jobs and trim other costs to remain competitive against regional rivals.
Japan's largest carrier wants to make savings of 75bn yen ($721m; £375m) by the end of 2007.