Ministry of Defence officials were trying to contact the Pentagon, whose domain name is ".mil", but accidentally sent the mails to Mali, which has the domain name ".ml", the Times newspaper reported.
Mali has cultivated close ties with Russia since a 2021 coup while distancing itself from former colonial power France and other Western nations. Last month authorities asked a U.N. peacekeeping force to leave the country.
Britain said the information that was mistakenly shared was not highly sensitive.
"We have opened an investigation after a small number of emails were mistakenly forwarded to an incorrect email domain," a spokesperson for the Ministry of Defence (MoD) said, without confirming the domain's name.
"We are confident they did not contain any information that could compromise operational security or technical data."
Last week a Financial Times investigation said millions of U.S. military emails had been misdirected to Mali's domain over the course of years due to the prevalence of such typos.
British media made light of the incident, with the BBC running the headline "You've Got Mali," a deliberately inaccurate reference to a 1998 Tom Hanks and Meg Ryan romcom.
Britain's MoD indicated it was taking the incident seriously, while downplaying the significance of what was sent in error.
"All sensitive information is shared on systems designed to minimise the risk of misdirection," the spokesperson said.
"The MOD constantly reviews its processes and is currently undertaking a programme of work to improve information management, data loss prevention, and the control of sensitive information."
(Reporting by Alistair Smout; editing by John Stonestreet)
