Crown attorney Scott Morrison said Friday outside court that the men are alleged to have participated in a "group sexual assault" in a barracks at CFB Shearwater on April 10.
The men were arrested Thursday morning and were in Nova Scotia participating in a hockey tournament with local Armed Forces personnel, he said.
A court document shows all four men who have been charged with sexually assaulting a woman are from the United Kingdom. It lists them as Craig Stoner, 24, of Stonehouse, Darren Smalley, 35, of Gosport, Joshua Finbow, 23, of Broughton Stockbridge, and Simon Radford, 31, of Lower Gosport.
Morrison said all of the men are British citizens.
A duty counsel lawyer is negotiating with the Crown on bail terms and the men are scheduled to return to court on Monday to continue those negotiations, Morrison said. The Crown has to determine whether they can be released and whether that would include allowing them to return to the U.K., he added.
The men are being held at the Central Nova Scotia Correctional Facility in Halifax.
Morrison declined to release any details about the complainant in the case.
Asked about jurisdiction in the case, Morrison said the Crown has jurisdiction over all Criminal Code offences in the province.
"There may be a mechanism where the British military could take jurisdiction over this, but my understanding is that the province of Nova Scotia has jurisdiction," he said.
"Our position at this point is that they have to stay in Canada. They can't leave the country."
Maj. Yves Desbiens, a spokesman for the Canadian Forces Military Police Group, said the allegations are serious and the complainant is a civilian.
"This is more than undesired touching," he said.
"This is taken very seriously. ... We will continue to work hard to bring this matter to a court."
The commanding officer of the Canadian Forces National Investigation Service said British authorities have co-operated with its investigation.
"This is a disturbing accusation of sexual assault," Lt.-Col. Francis Bolduc said in a statement. "I'm pleased with the full co-operation provided by the British authorities to support the hard work and diligence of the CFNIS team in responding to this matter."
The investigation service is a unit within the Canadian Forces Military Police Group and investigates serious and sensitive matters relating to the Defence Department.
The British Ministry of Defence said it would assist Canadian authorities, but declined to comment any further in a statement.
"The Royal Navy takes allegations of this nature very seriously, however as legal proceedings continue it would be inappropriate to comment further," it said.
CORRECTION: An earlier headline wrongfully identified the accused as "Canadian Royal Navy" members. This version has been updated.