Two missing US balloonists are feared dead after their craft suffered "a sudden and unexpected failure" over the Adriatic.
Organisers of the Gordon Bennett Gas Balloon Race said Richard Abruzzo and Carol Rymer Davis were likely to have been killed in a tragic accident off the Italian coast.
The US pair have been missing since Wednesday morning when race organisers lost contact with them as they were flying between Italy and Croatia.
They were one of 20 teams that set off on Saturday night from farmland near Bristol in the annual race to fly the furthest distance.
Helicopters, military aircraft and three boats had been taking part in the hunt for the Americans, which was led by the Italian coastguard.
Organisers said they had analysed data received from tracking units in the Adriatic shortly before contact was lost with the US balloon and believed something terrible had happened.
On Friday night a race spokesman said: "Both families have been informed that the control centre received recorded transponder readings from the air traffic control unit local to the area where the balloon had last been tracked. Transponder readings show the height, time and location of a balloon in a coded form.
"The control centre has examined the transponder readings from Abruzzo and Rymer Davis' balloon and calculated the change in height of the balloon over the time period recorded. The data show that the balloon had a moderate descent rate initially which then increased into a high rate of descent, to around 50mph.
"This is very pessimistic information. At this rate of descent to the surface, survival would be unlikely. It is the opinion of the Gordon Bennett 2010 flight control team that the balloon appears to have suffered a sudden and unexpected failure. The cause of this tragedy is still being examined."
Mr Abruzzo's sister-in-law, Sandra Abruzzo, of Albuquerque, New Mexico, said she had been told the balloonists had suffered "an issue with the electrical" components in the balloon, and speculated that the loss of contact could be related to that.