A baggage system problem has caused delays to British Airways passengers at Heathrow Airport.
Travellers were earlier unable to check in baggage at Terminal five (T5) due to a computer problem.
The airport says the problem has been resolved, but some passengers face long queues and delays.
BBC reporter Keith Doyle said there was a queue of about "500 people waiting to rebook flights".
Simon Frusher, who was flying to New York, said: "There are now thousands of people with missed flights, as planes went on time.
"Huge queues now for rebooking... unsure as yet what flight we can get."
An airport spokesperson said: "Our teams have now restored all check-in services and we have additional staff in the terminal to help passengers."
The airport said passengers who wished to take hand luggage on board were unaffected, but others were prevented from checking in and unable to travel.
Mr Doyle said a separate area had been set aside for rebooking flights at T5, which operates British Airways flights.
A BA spokesman apologised for the inconvenience and said "all of our flights continue to operate as normal".
The problems started at around 09:00 BST and were resolved by 11:30.
T5 was criticised following its opening day in March 2008 when hundreds of bags went astray and there were long flight delays, but the terminal has had few problems since then.