Heathrow Airport has asked airlines flying from Terminals 2 and 3 to cancel 10 per cent of their flights after a technical glitch caused baggage problems.
Around 5,000 passengers on approximately 30 flights are believed to have been impacted.
The cases were spotted by Sky News defence and security correspondent Deborah Haynes.
She left Heathrow’s Terminal 2 after an early-evening arrival from Brussels and said: "The warning signs that all was not well were clear at baggage claim.
"There were clusters of suitcases without owners grouped around conveyor belts."
Bosses at the airport said a “technical glitch” had caused the backlog, which was described by onlookers as resembling a “carpet of luggage”.
Heathrow apologised for the disruption and has now asked airlines to “consolidate their schedules” on Monday.
A Heathrow spokesperson said: “We apologise unreservedly for the disruption passengers have faced over the course of this weekend. The technical issues affecting baggage systems have led to us making the decision to request airlines operating in Terminals 2 and 3 to consolidate their schedules on Monday 20th June.
“This will enable us to minimise ongoing impact and we ask that all passengers check with their airlines for the latest information.”
Chaos is widespread across the UK, with a pilot seen putting bags on an Edelweiss flight at Edinburgh airport on Sunday as airlines continue to struggle with ongoing staff shortages.
Transport Secretary Grant Shapps called for better pay for baggage handlers and others to attract more airport job applicants.
Airports have been urged to cancel more flights over the summer to avoid chaotic scenes. Gatwick is cutting 4,000 daily flights throughout August.
Thousands of workers in the aviation industry were laid off during Covid when world flights were axed.
EasyJet announced it is cancelling summer flights in a bid to avoid last-minute cancellations and in response to caps introduced by Gatwick and Amsterdam Schiphol airports.
It said it is “proactively consolidating a number of flights across affected airports”.
The aviation sector across Europe is experiencing “operational issues” including air traffic control delays, staff shortages in ground handling and at airports, and increased times for identity checks of new recruits, easyJet said.
The airline has cancelled thousands of flights in recent months, particularly during school holidays at Easter and the half-term period, which coincided with the Jubilee bank holiday weekend.
Chief executive Johan Lundgren told reporters “I can’t tell you how many flights will be impacted” as “we need to work this through”.
He added: “It would be misleading for me to give any numbers today because we simply don’t know.”