SYDNEY, Australia (AP) _ Three people who say they suffered potentially fatal blood clots during long flights have sued three international airlines.

South African Debbie Daniels and Australians Naomi Forsyth and Lawrie Gillott filed damage claims Tuesday against Qantas Airways, KLM Royal Dutch Airlines and British Airways, as well as the Civil Aviation Safety Authority in Australia.

Their law firm, Slater & Gordon, said it is seeking unspecified damages in the Victoria state Supreme Court. The airlines and CASA declined comment or said they did not know about the case.

Reports of passengers developing clots after long flights have mounted since media coverage of the October death of a young woman during a flight from Australia to London. ``Not until then did many who suffered illness realize that they were not alone,'' lawyer Paul Henderson said.

In March, World Health Organization medical experts and airline representatives meeting in Switzerland said there is likely a link between long-haul flights and deadly blood clots.

Clots develop in blood vessels in the legs when circulation slows, usually because people stay still for long periods. The condition is known as deep vein thrombosis. The clots can be fatal if they break off and are carried to the lungs, blocking the flow of blood.

The lawyers said Gillott collapsed at London's Heathrow Airport, Forsyth risks permanent leg injury, and Daniels suffered brain damage after a cerebral hemorrhage.