Fox-Pitt Kelton (FPK) anaylsts have estimated the business interruption costs of the New York disaster could run to $5bn (£3.15bn).
FPK analysts have been reported as saying the cost was likely to be between $2bn (£1.36bn) and $3bn (£2.04bn) but FPK London insurance analyst William Hawkins said it could be as high as $5bn (£3.4bn).
Thousands of businesses have been unable to trade in Lower Manhattan because of the collapse of the World Trade Centre.
Hawkins said the 1993 terrorist bombing of the World Trade Centre cost $510m (£346m), primarily in business interruption losses, since there was little material damage.
He said the cost of this disaster would be much higher, although how much was not yet possible to tell.
Most of the businesses within the centre are likely to have had a business interruption clause in their property policies, but some in the surrounding area may not be paid-out for the economic losses arising from the area's closure, Hawkins said.
Some businesses are not expected to be running normally for at least a year.
It is expected that part of these losses will be covered by the US government, which has set aside $20bn (£13bn) of its $40bn (£26bn) aid package for recovery.
