British Airways has said a "significant" number of passengers are still without their luggage after the airline's major system failure.
The company apologised to those who have not been reunited with their bags after travellers were stranded at airports over the bank holiday weekend.
A spokesman for BA was unable to say when all bags were expected to be returned, saying: "We are going as quickly as we can."
In the latest update for passengers on its website, the airline said: "Although we have already flown many bags to the correct airport, there is still some work to do and we know there are still significant numbers of customers who are yet to receive their luggage."
Passengers left without luggage are being advised they can claim money back for essential items.
The BA spokesman added: "We are very sorry for the frustration customers are experiencing and understand the difficulties they are facing.
"We're working round the clock to reunite customers with their luggage. We are delivering bags to customers, at homes or hotels, as soon as the bags arrive at their final destination."
Experts predict the knock-on effect of the IT outage could continue for several days and BA is facing huge compensation costs, with reports suggesting the bill could top £100 million.
The airline's parent company, IAG, saw shares fall by around 3% in the first day of trading in London after the problem emerged.
BA has said there is no evidence it was the victim of a cyber attack and added the cause of the IT issues was a surge after "total" power failure.
The spokesman said: "It was not an IT issue, it was a power issue. There was a total loss of power.
"The power then returned in an uncontrolled way, causing physical damage to the IT servers.
"We know what happened, we are investigating why it happened."
BA chief executive Alex Cruz has promised a full investigation into the failure, which affected 75,000 passengers as thousands of flights were cancelled.
On Saturday night, travellers spent the night sleeping on yoga mats spread on terminal floors after BA cancelled all flights leaving the London hubs, while disruption continued into Sunday with dozens more services from Heathrow axed.
Mr Cruz said the outsourcing of jobs was not to blame for the "catastrophic" IT failure.
BA was accused of greed after the GMB union suggested the disruption could have been prevented if the beleaguered airline had not cut "hundreds of dedicated and loyal" IT staff and contracted the work to India last year.
The airline said it has a freephone number - 0800 727 800 - for people affected by the IT failure and customers are advised to check ba.com.