— The damage caused by airplanes that crashed into New York‘s World Trade Center Tuesday will cost insurers worldwide billions of dollars, in what may be the most expensive man-made insured event ever.

``It is safe to assume claims will be in the billions,' said Robert Hartwig, chief economist for the Insurance Information Institute in New York, who witnessed the crashes.

The total bill, which could take years to establish, is likely to top the $3 billion insurers paid out for the Piper Alpha oil platform explosion off the coast of Britain in 1988, the most expensive man-made event to date.

It will certainly be the most expensive man-made insurance loss in U.S. history, topping the $775 million paid out after the Los Angeles riots of 1992.

``You just can‘t quantify it in terms of cost,' said an insurance analyst who asked not to be named.