A "significant number of customers" are still without their luggage after a British Airways IT failure that caused global flight disruption.
The airline said although it was moving to get bags back to passengers, there was still some work to do.
On Monday night it posted an update on its website saying: "We are continuing to make good progress in reuniting bags with customers around the world who were affected by the major IT systems failure on Saturday.
"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.
"We are very sorry for the frustration this situation is causing at a very busy time of year for holidays."
Earlier the airline's chief executive said the outsourcing of jobs was not to blame for a "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 in 2016.
But the airline's chief executive Alex Cruz said this was not the case, adding that a full investigation would be conducted into the failure which affected 75,000 passengers.
He told Sky News: "I can confirm that all the parties involved around this particular event have not been involved in any type of outsourcing in any foreign country.
"They have all been local issues around a local data centre who has been managed and fixed by local resources."
Mr Cruz said: "On Saturday morning at around 9.30 there was indeed a power surge that had a catastrophic effect over some communications hardware which eventually affected all the messaging across our systems.
"We will have completed an exhaustive investigation on exactly the reasons of why this happened. We will, of course, share those conclusions once we have actually finished them.
"We have no evidence whatsoever that there was any cyber attack of any sort."
Mr Cruz apologised "profusely" for the hardship caused to customers and insisted a similar incident would never happen again.
He further offered assurances that no customer data or any list, including terror watch lists, had been compromised by the glitch.
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.
The IT outage had a knock-on effect on BA services around the world, while passengers who did get moving on the limited number of flights to take off from the UK reported arriving at their destinations without their luggage.
The disruption also hit transport systems on the ground, with hundreds of travellers flooding London's King's Cross station in hope of boarding a train north instead.
Experts predict the knock-on effect could continue for several days and BA is facing huge compensation costs, with reports suggesting the bill could top £100 million.
Mr Cruz said the airline was "committed" to following all compensation rules.