The number of London hotel rooms booked by Americans fell by 45% in September, following the terror attacks in New York and Washington.

Accountancy and business consultancy company PKF also found a 17% overall drop in rooms booked in the capital compared to September last year.

The survey indicates that the situation deteriorated further in October with many five-star establishments reporting they are only half full in what should be one of their strongest months.

Americans are by far the biggest group of overseas visitors to London - but the 11 September suicide hijack attacks have deterred many from travelling.

Jobs jeopardy

More than 250,000 people are employed in the tourism industry in London - but jobs could be in jeopardy if, as many hoteliers fear, the Americans stay away for some time.

The British Tourist Authority has estimated that the UK, whose tourism industry is dependent largely on US trade, could lose �2.5bn in revenue from overseas visitors next year.

But a separate survey published on Monday indicates that the US is the top choice for UK holidaymakers, favoured by more than one in 10 people.

Confidence was highest among experienced business travellers, with more than one in five executives saying they would holiday in the US, the poll, for Marks & Spencer's Financial Services, found.

Married people were more concerned about travelling to the US than single people, with men more likely than women to cite America as their top holiday destination.