The US Congress must pass a 15-year extension of the nation's terrorism insurance legislation to shield businesses from the economic fallout of a future attack, according to insurance lobbyists.

The Insurance Information Institute (III) says the Terror Risk Insurance Revision and Extension Act (TRIREA) is crucial for insurers to price risks at an affordable level for consumers.

The House of Representatives Rules Committee was due to meet this week to set clear guidelines for the Act, which must also be passed by the Senate and President Bush to come into effect.

The Bush Administration opposes the bill, which adds life insurance to covered lines while removing ambiguities around the definition of domestic and international attacks.

The existing terrorism insurance act expires at the end of the year.

III President Robert Hartwig says various attack scenarios show insurance losses several times that of September 11, which cost the industry about $US36 billion ($42 billion).

"It is essential that a long-term terrorism risk insurance program be enacted," he said. "Implementation of such a measure is a key component of the nation's effort to protect the financial homeland.

"Businesses in cities and towns, large and small, from coast to coast would, under this proposal, be able to purchase terrorism risk insurance more readily and be secure in the knowledge that the protection will remain available for many years to come."