Airlines and tour operators are unlikely to be insured for business losses resulting from the US terrorist attacks, according to industry insiders.

British Airways is understood to have been losing £6m per day since international flights were stopped and holiday companies are being hit by a booking slump and a wave of cancellations.

Continental Airlines, the US's fifth-largest airline, is laying off 12,000 people in response to the attacks.

A specialist aviation broker said: “Business interruption policies were never designed to cover this sort of thing. They would usually cover damage to the aircraft, but not the cancellation of hundreds of flights.”

A Lloyd's insider said: “99% of airlines do not buy business interruption. They will be hurt by both the increase in oil prices and the drop in passenger revenue.”

United Airlines and American Airlines, the two biggest carriers in the US, each have $1.5bn (£1bn) of liability insurance, but there are concerns that lawsuits from the owners of the World Trade Centre, as well as the families of those killed on the ground, will far exceed this amount.

Some companies are expected to implement Chapter 11 of the US bankruptcy code, which states that a company can put in a “reorganisation plan” before its creditors, outlining a survival strategy.

Head of advocacy at law firm Linklaters, Mark Humphries, said: “There will be a severe downturn in the airline industry because of this disaster. Naturally, there will be a number of failures and US airlines may go into Chapter 11, or seek to take Chapter 11 for their own protection and to protect shareholders.”

The Bush administration has pledged $40bn (£27bn) to help businesses affected by the crisis, to pay for counter-terrorism and recovery efforts, some of which will go to airlines.