A passenger plane which crashed in a remote Amazon region collided with another aircraft, Brazilian aviation officials have confirmed.
Rescuers have struggle to reach the aircraft in dense jungle
The Boeing 737, flying from Manaus to the capital, Brasilia, crashed in the Amazon rainforest on Friday.
All 155 passengers and crew are presumed dead after rescuers reported finding bodies but no survivors.
Aviation officials are investigating the possibility the plane and a smaller executive jet clipped each other.
Denise Abreu, director of the National Civil Aviation Agency (ANAC), told reporters on Sunday that a mid-air collision occurred, but did not release any other details.
Earlier, another aviation official said it was "highly probable" that a collision between the two aircraft caused the crash.
An executive jet made a forced landing with a damaged wing near the crash site on Friday.
Everyone on it survived, but its pilot reported seeing a shadow and hearing a noise.
Aviation officials were interviewing the jet's passengers and crew, while investigators had removed the aircraft's black box for analysis, another aviation official said.
With no survivors located, the crash becomes Brazil's worst air disaster.
President Luiz Inacio Lula da Silva has declared three days of national mourning.
Search and rescue efforts have been hampered by the remote location of the crash site and the dense rainforest.
The first rescuers on the scene had to abseil down from helicopters and then clear an area for the vehicles to land.
The plane was operated by the budget airline Gol, which has expanded rapidly since it was establish in 2001 to become Brazil's number two carrier.
Gol says the plane involved was new, having come into service this month.