France scrambled a fighter aircraft Sunday after a jetliner slightly veered from its course and lost radio contact with the ground over western France, military officials said.
The Washington-bound United Airlines Boeing had taken off in Rome, the air force information service SIRPA said.
Airline officials declined to confirm or deny the incident when contacted by AFP.
The Rafale fighter aircraft reached the jet after a brief supersonic flight between the towns of La Roche-sur-Yon and Nantes near the Atlantic coast, where the radio contact was re-established. The passenger jet then pursued its course.
Firefighters in the area said they received a number of phone calls from alarmed residents after the fighter jet broke the sound barrier about 100 kilometres (60 miles) south of Bordeaux at a cruising altitude of 35,000 feet (10,700 metres).
@TheLocalFrance Could feel the pressure wave plus boom. Went to end of garden to check nuclear power station. Not joking.— Bill Tingle (@devonbill) May 5, 2014
"What was that explosion or boom around Bordeaux that shook all the houses??" said another alarmed resident on Twitter.
c'est quoi cette explosion/boum à #bordeaux qui a fait vibrer toutes nos maisons ???— Laurent Rochette (@LaurentRochette) May 4, 2014
Military officials said that in incidents such as Sunday's the pilot of the fighter jet would position himself to the left of the plane with the pilot of the jetliner in full view to identify the problem in line with international regulations.
Sunday's incident followed "a normal procedure as is done dozens of times every year," SIRPA said. About 70 such situations were recorded last year.