It has become customary for the Pope to return home from official visits on the flag carrier of the country he has toured.
But Pope Benedict XVI will instead fly from Rome to Britain and back on an Airbus A320 operated by Italian state airline Alitalia.
One factor understood to have concerned Roman Catholic officials was the BA cabin crew strikes, which threaten to restart in September when the visit takes place.
The Vatican is determined nothing should detract from the four-day trip, the first state visit by a Pope to Britain.
He will meet the Queen in Scotland before visiting London and Birmingham.
British Airways was asked earlier this year to provide a quote to charter a 747 jet to fly the Pope back to Rome.
A BA source said it offered a quote at ‘commercial rates’, but heard no more from the Church.
Airline officials assumed the Vatican had been given a cheaper quote by a rival.
Vatican sources, however, claim Church officials in the UK tried to contact BA again to discuss the details but received no response.
A senior source in the Catholic Church in Britain said the decision to use Alitalia
throughout the trip was made as it was the easier, cheaper option.
He said: ‘The Vatican normally offers the flagship airline of the host nation the opportunity to fly the Pope back to Rome at the end of a visit, though there are exceptions.
'In this case, because it is such a short visit, it made more sense to stick with Alitalia. There is no bad feeling with BA.’
SIC: DMUK