The incident occurred while the two men were shooting a scene involving an explosion in a rubber boat near a dam on Lake Ognyanovo in southwestern Bulgaria last Thursday, media reports said.
The accident "resulted in one fatality and one injury," said a spokesman for the production, while the Sofia Echo English-language newspaper said the injured man underwent five hours of surgery.
The main production unit for the movie, written by Sylvester Stallone, was shooting in the mountain resort village of Bansko, two and a half hours away, said the spokesman.
"It is with great regret that we confirm this unfortunate accident," added a statement by producers Image/Millennium Films. "Our hearts go out to the families and those on the production affected by this tragedy.
"The filmmakers are working closely with the authorities in responding to and investigating this accident," it added, giving no further details of the incident.
"The Expendables 2," starring "Rocky" actor Stallone as well as Arnold Schwarzenegger, Bruce Willis and Jean-Claude Van Damme, is a follow-up to the 2010 action blockbuster.
The sequel is due for release in August next year. (AFP)
