Terminally ill Dorothy Rostron flew to Fuengirola from Manchester with her family for a final holiday together last month.
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But on the return flight all four members of the family were blocked from flying back.
Bosses at the airline say they allow passengers to carry bottled oxygen if required, but these could not be the liquid oxygen containers for safety reasons, the Manchester Evening News reported .
The 82-year-old, from Burnley, suffers from a chronic lung condition and relies on oxygen canisters to keep breathing.
After taking an hour carrying out checks easyJet allegedly told the family the canisters posed a "security risk" and took them off the flight.
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They were then forced to arrange emergency oxygen for Dorothy while they waited in Malaga Airport to find out if they could return home.
Eventually, Norwegian Airlines said they could fly back to Manchester on a later flight.
Before making the decision to take the trip the family say they carried out relevant checks with Easyjet and filled in paperwork.
They also paid out £3,000 in travel insurance.
Dorothy's son-in-law, Donnie Doran, said: "My wife contacted EasyJet with details of the oxygen canisters. They said the type was ok.
"The trip going out from Manchester was fine, when we arrived they looked after us. The return flight has been horrendous.
"They said nobody was allowed to fly, we provided the information, showed them the bottles and everything else.
"We have never been so embarrassed in our lives. They were doing checks on the gas as we sat down on the plane.
"After 45 minutes of sitting down there was a number of discussions with the head stewards and the pilot safety officer.
"They came and said we were not allowed, everyone was not allowed to fly all four of us."
Donnie, 58, added: "I think it is disability discrimination. We provided all of the information, if they had a problem they should not have allowed us to fly with them in the first place.
"We did everything they asked of us. We felt like we were terrorists that we were a security issue for the flight.
"Try telling that to an 82 year old woman this was a security issue."
An easyJet spokeswoman said: "easyJet apologises that a passenger was denied travel from flight EZY1924 flying from Malaga to Manchester on 19 December as a result of having conflicting paperwork to support the use of their own oxygen supply during the flight.
"easyJet allows passengers to carry up to two oxygen cylinders free of charge with a doctor's note specifying the requirement for carriage, however this cannot be liquid oxygen. Unfortunately the oxygen this passenger was carrying was produced by a company called Liquid Oxygen which was clearly stated on the bottle. As a result of this extra checks needed to be carried out in order for them to receive clearance to fly with the oxygen.
"Our ground staff advised the passenger of this and offered overnight accommodation and a free of charge transfer onto the next available flight. The passenger decided to travel with an alternate carrier back to the UK today.
"The safety and wellbeing of its passengers and crew is Easyjet's highest priority."