British Airways passengers claiming compensation for the bank holiday travel chaos are being "passed from pillar to post", an insurance industry body has warned.
The airline promised to compensate customers for "welfare claims" such as hotels, meals and phone calls, on top of pay outs of up to 600 euro (£524) for delayed or cancelled flights.
But a form entitled "Make a claim for disruption expenses" on BA's website informs customers with travel insurance that they must seek compensation through their insurer before submitting a claim to the airline.
The web page does not specify if excess costs included in insurance policies will be refunded by BA.
Some 75,000 passengers were stranded by the IT shutdown following a power surge on Saturday.
The Association of British Insurers (ABI), which represents more than 250 UK insurance firms, said in a statement: "People affected by the disruption should be able to claim compensation and refunds for any expenses as simply as possible, not be passed from pillar to post.
"EU flight compensation regulations set out that airline operators should provide compensation to passengers that suffer long delays or cancellations.
"Those affected should seek compensation, and any refunds of expenses, in the first instance from British Airways. Any cover available under travel insurance will usually kick in only if compensation is not available from any other source."
A BA spokesman said the airline has been encouraging customers to submit claims for their expenses, including those beyond flights.
He went on: "We have created a dedicated page on ba.com providing customers with all the information they need to make a claim.
"We are in the process of updating the wording on our claims page to ensure our customers have clear information."
Mystery surrounds the cause of the power surge, with National Grid and local energy providers saying there had been no supply issues on Saturday.
A BA computer worker has accused the company of ignoring warnings about outsourcing work and cutting jobs over the past year.
The man, who did not want to be named, said Heathrow had been hit by power outages in the past, but BA's system was always resilient enough to be protected.
He told the Press Association that 600 IT jobs had been lost since March last year, with work being outsourced to India.
The GMB union called on BA to halt any further job cuts and to bring IT work back in-house from India.
BA said: "We would never compromise the integrity and security of our IT systems. IT services are now provided globally by a range of suppliers and this is very common practice across all industries and the UK Government.
"The incident on Saturday was not an IT issue, it was a power issue."