A transatlantic flight was forced to divert to Dublin Airport after a number of cabin crew and passengers were reportedly affected by fumes from a spillage of a cleaning solution.
It is understood that a number of people on board complained of feeling unwell while two flight attendants are believed to have lost consciousness briefly.
The affected passengers complained of suffering from "burning eyes" and "itchy skin" following the incident which occurred in the galley.
American Airlines flight AA-729 was travelling from London to Philadelphia at the time.
The Airbus A330-300 jet, with 287 passengers and a crew of 12 on board, was about 250km southwest of Valentia in Co Kerry when crew made contact with air traffic controllers to advise them of their emergency.
The crew advised controllers of the problem on board and that they wished to divert.
The crew reported that the cause of the diversion was a leaking bottle of an "ammonium-based cleaning product" that had been left in a lavatory.
The crew also requested that paramedics be available to meet the aircraft on arrival at Dublin.
Airport fire and medical crews were placed on standby and National Ambulance Service resources were also dispatched to the airport.
Two flight attendants and one passenger were taken to hospital for treatment on landing.
A spokesperson for American Airlines said: "Flight 729 from London Heathrow to Philadelphia diverted to Dublin due to an odour caused by a spilled cleaning solution.
"The flight landed safely in Dublin and taxied to the gate. Medical personnel have met the aircraft to evaluate any crew members or passengers who may need additional assistance," the airline added.
Spokesperson for Dublin Airport, Siobhán O'Donnell, said: "American Airlines flight AA729 on route from London Heathrow to Philadelphia was diverted into Dublin Airport for a medical emergency. The aircraft landed safely at approximately 1.20pm.
"As per standard operating procedures there was a full turn out of Dublin Airport's emergency fire services," Ms O'Donnell added.
The flight was later cancelled and passengers were provided with overnight hotel accommodation.
Later, a second American Airlines flight turned around over the Atlantic and also diverted to Dublin Airport.
Flight AA-787 was travelling from Paris, to Charlotte, North Carolina, when the crew made a U-turn about 300km southwest of Ireland.
The crew reported that a male passenger on board was unwell.
The flight landed at around 3pm and was met by medical personnel.
The passenger was taken to hospital for treatment and the plane resumed its journey at around 5.30pm.