Four British men were on board a small aircraft that went missing off the north-east coast of Brazil on Friday.
The Foreign Office confirmed that Alan Kempson, Sean Woodall, Ricky Every and Nigel Hodges were on board.
All four's next of kin have been informed, the spokeswoman said. It is understood that three of the four do not live in the UK.
An eyewitness claims to have seen the plane go down after losing power. A search is now under way near Ilheus.
The plane had taken off from Salvador, capital of Bahia state, and the Brazilian pilots had last made contact with air-traffic controllers before dusk on Friday as the plane cruised over the Atlantic coast en route to the resort town of Ilheus, according to the airline Aero Star.
Business manager Ellen Duarte added the weather had been good and the pilots had not reported any problems with the plane.
"It was flying perfectly," Ms Duarte said. "The pilot said he was making a visual approach to the airport, and that was the last we heard."
Brazil's coast guard and three Aero Star helicopters searched for signs of a crash, but found nothing, she said. Bahia state police and air rescue have joined the search.