Hundreds of passengers have been left stranded in Britain after airline Qantas grounded all of its flights because of a bitter industrial dispute.
The Australian national carrier grounded its global fleet indefinitely until unions representing pilots and ground staff reach an agreement with the airline over pay and conditions.
A Heathrow spokesman said four Qantas liveried planes were due to take off from the airport - meaning hundreds of passengers who were scheduled to depart are now unable to fly.
British passengers abroad who are due to use the carrier will also face travel disruption.
The Foreign Office issued a statement advising those due to travel with the airline in the next 48 hours to check on the Qantas website or to consult their tour operator.
The carrier plans to "lock out" all employees involved with industrial action from Monday evening. Staff will not be required to turn up at work and will not be paid.
The airline had been forced to reduce and reschedule flights for weeks because of a series of strikes over staff concerns that their jobs are being moved overseas.
A Qantas spokesman said 600 flights have been cancelled because of the industrial action - affecting 70,000 passengers.
The strikes have cost the airline 15 million Australian dollars (£10 million) a week.
Flights already in the air when the announcement was made were continuing to their destinations but all others were cancelled. The airline said customers booked on Qantas flights should not go to the airport until further notice and a full refund would be available for those affected.