Updated at 2:29 p.m. ET
U.S. and Croatian search and rescue teams joined an expanded Italian coast guard search Thursday for two American balloonists who disappeared in rough weather over the Adriatic.
The United States offered two Navy aircraft to join in the search and one was put to work Thursday afternoon, said Italian Coast Guard Lt. Massimo Maccheroni.
Croatian coastal aircraft crews were scouring the area around Croatia's distant, uninhabited islet of Palagruza, said Marina Haluzan, the spokeswoman for the Croatian Ministry of the Sea and Transport.
"There's no news so far about the missing balloon," she said in a statement, adding that Croatian and Italian coastal authorities were in touch and coordinating the search.
Veteran balloon pilots Richard Abruzzo and Carol Rymer-Davis were participating in the 54th Gordon Bennett Gas Balloon Race when .
Their balloon was equipped with a satellite telephone, VHF radios, radar transponder and two mobile telephones. No signal has been detected from the balloon's Emergency Location Transmitter, which should activate on contact with water.
"They could not possibly still be flying," said flight director Don Cameron. "If they are on land, they must be in a very remote place. Otherwise we would have heard from them by now."
Palagruza is located in the middle of the Adriatic Sea, 60 nautical miles from the Croatian coast and 29 nautical miles from Italian coast.
On Thursday, the Italian Maritime Rescue Coordination Center expanded its search to 14 miles off the Italian coast, with five boats, several aircraft and a helicopter involved.
Abruzzo, 47, of Albuquerque, New Mexico and Davis, 65, of Denver, Colorado, are experienced balloonists and won the 2004 edition of the Gordon Bennett race from Thionville, France, to Vannas, Sweden.
In the race, teams try to fly the farthest on a maximum of about 1,000 cubic meters of gas.
Abruzzo is the son of famed balloonist Ben Abruzzo, who was in 1981 part of the first team to cross the Pacific Ocean by balloon, and who was killed in a small airplane crash in 1985.
New Mexico Gov. Bill Richardson successfully arranged for the U.S. military forces to join the search.
"I've been following the search for Richard and Carol all day, and I'm optimistic that they will be located," Richardson said. "I've been in contact with the Abruzzo family and have offered any help they need in getting Richard back home to them safely. My thoughts are also with Carol's family as they await word on their loved one."
In the 2005 Gordon Bennett race, Richard Abruzzo and Davis hit a power line in Kansas. Abruzzo fell out, suffering several broken bones. Davis landed the balloon safely, although she suffered bruises when she was dragged along the ground while landing the lightly loaded balloon in 40 knot winds.
Abruzzo and Davis finished third in the 2006 America's Challenge gas balloon race by traveling 1,478 miles from the Albuquerque International Balloon Fiesta.
Word of their disappearance came on the eve of New Mexico's annual balloon fiesta.
Ben Abruzzo and two other Albuquerque residents, Maxie Anderson and Larry Newman, made the first successful balloon flight over the Atlantic in a helium-filled balloon in 1978, landing in France after a flight of 137 hours.
Garth Sonnenberg of Albuquerque, a friend of Abruzzo's, said Wednesday that he had heard that the balloonists had problems with their radio throughout the flight. "We're hoping that it's a good possibility that it's just a radio problem," he said.