The four men - Craig Stoner, Darren Smalley, Joshua Finbow and Simon Radford - were members of a British Navy hockey team that was in the Atlantic province for a tournament, according to the spokesman.
The department said the men were charged by a special unit within the military police that has a mandate to investigate serious and sensitive matters.
The assault allegedly took place at a party and involved a Halifax-area woman, the local Chronicle-Herald newspaper reported.
"This is a disturbing accusation of sexual assault," Canadian Forces Lieutenant-Colonel Francis Bolduc said in a statement. "I'm pleased with the full cooperation provided by the British authorities to support the hard work and diligence of the (investigative) team in responding to this matter."
Representatives for the accused could not immediately be reached for comment.