The Sars outbreak and the Iraqi war are being blamed for a big dip in the number of overseas visitors to the UK.
The largest fall was among visitors from North America
The latest official figures show foreign tourists made 1.83 million visits to the UK in April, 15 percent fewer than during the same month last year.
Visits by North Americans fell 18 percent to 250,000, while western European visits slumped 14% percent to 1.32 million, according to the Office for National Statistics.
The VisitBritain organisation, which has replaced the British Tourist Association, said the predicted decline was due "in large part to a combination of the Sars outbreak around the world and the war with Iraq depressing long-haul travel and particularly affecting visits from North America".
The company's chief executive, Tom Wright, said: "Until we have results for May, it is difficult to predict performance for the early summer months in advance of the key travel period between July and September.
"Anecdotal evidence from the industry here in Britain, together with feedback from VisitBritain's overseas offices, indicates that demand for Britain as a destination remains high in many of our key markets and that a relatively swift recovery is only around the corner."
The amount spent in the UK by foreign visitors in April also fell, to £740 million, 15 percent down on the figure for the same period last year.
Although visitor numbers in April were down, the number of overseas visits for the first four months of this year, at 6.76 million, is actually up one percent on January to April 2002.
However, the number of North American visits fell 12 percent.
The statistics also showed that UK residents were less likely to leave the country in April, with 4.69 million trips abroad, compared with 4.83 million visits in April 2002
Between January and April this year UK residents made 15.68 million trips abroad, one percent fewer than in the first four months last year.
The figures were released as struggling tour operator MyTravel, whose brands include Airtours and Going Places, announced that it made a pre-tax loss of £618m in the first six months of the financial year.
The company said it had signed a £1.3bn refinancing deal with its lenders which would allow it to turn the business around.