Insurance companies can't promise full coverage for property damage from a terror attack without federal help, industry leaders told a House panel Tuesday.

But nearly five years after the Sept. 11 terror attacks, lawmakers warned the industry that Congress cannot remain a last-resort insurer for terrorism-related losses.

At issue is whether Congress will again extend the Terrorism Risk Insurance Act to reimburse insurance companies up to $100 billion should terrorists strike again — a measure criticized by many as a favor to insurance corporations. The 2002 act was set to expire last December 31, but Congress extended it for two more years.

"If another 9/11 attack occurs and people do not have insurance, there won't be anyone to pay those losses, other than the federal government," said Jeffrey D. DeBoer, president of the Real Estate Roundtable, representing the nation's top 100 privately owned and publicly held real estate ownership development.

The Sept. 11, 2001, attacks hit insurance companies hard, costing them at least $32 billion in claims and prompting many to exclude terrorism from coverage. Without insurance, a terrorist strike could heavily damage the economy because businesses would have trouble rebuilding and hiring again. The law does not allow the government to step in on any claims less than $50 million this year and $100 million in 2007.

Still, Rep. Luis V. Gutierrez, D-Ill., told industry officials at the joint House hearing of the Financial Services and Homeland Security committees that insurers should be working toward paying terror-related claims without government help.

"At this point, the market has not yet stabilized and the need for (the act) remains," Gutierrez said.

But "eventually the private market must adjust," Gutierrez said. "I do not want to see the federal government as a permanent re-insurer of last resort."

Private insurers, however, have a hard time estimating how much they will need to pay in losses, and "acts of terrorism are too difficult to predict and therefore exceedingly difficult to price," said Terry Fleming, director of the Risk and Insurance Management Society.

The industry also reported receiving inconsistent guidance and information from the Homeland Security Department about potential attacks or other risks.

"Without information on the nature of the threat, measuring risk becomes extremely difficult," said Rep. Rob Simmons, R-Conn.