ZURICH, Switzerland—Property and business interruption losses from the Sept. 11 terrorist attacks made 2001 by far the worst year on record for man-made disasters, but insured losses from natural catastrophes were below average last year, according to Swiss Reinsurance Co.

Worldwide, insured property and business interruption losses from man-made disasters totaled $24.4 billion in 2001, compared with an average of $5.9 billion per year for 1987 to 2001.

The property and business interruption losses from the attacks on the World Trade Center represent $19.9 billion of the total, according to Zurich-based Swiss Re. A further $30 billion to $58 billion in liability, life and health insurance claims are expected from the attack, Swiss Re said.

Natural catastrophes, meanwhile, caused $10 billion in property insurance losses in 2001, compared with an annual average of $14.3 billion for 1987 to 2001, according to Swiss Re.