The Islamist fanatics were all members of Al Qaeda in the Land of the Islamic Maghreb, which is the terror network's largest regional wing outside of the Middle East.
According to The Sun, they contracted the illness at a forest training camp in Algeria - and terror chiefs now fear it could spread to other cells.
The Black Death is a highly infectious disease that swept across the world in the Middle Ages, reducing Europe's population by as much as 60 per cent.
Around 2,500 cases of the plague still occur globally every year, but with proper medical care it rarely results in fatalities. Symptoms of the agonising disease include boils in the groin, neck and armpits.
The Al Qaeda epidemic broke out in Tizi Ouzou province, east of Algiers, and was only discovered when security forces found a cadaver by a roadside.
Terror boss Abdelmalek Droudka had evacuated his 1,000-strong camp in response, but because the infection can linger undetected in the body for days The Sun believes Al Qaeda chiefs are expecting further outbreaks.
A security source told the newspaper: "This is the deadliest weapon yet in the war against terror. Most of the terrorists do not have the basic medical supplies needed to treat the disease.
"It spreads quickly and kills within hours. This will be really worrying Al Qaeda."
No-one has suggested the group deliberately isolated the disease in preparation for an attack, but experts have previously warned that the Bubonic Plague is a viable weapon in biological warfare.
In 2004, the Ministry of Defence said it had developed a vaccine for the disease. At the time lead researcher Rick Titball told the BBC the Black Death is "one of the bio-terror agents about which we are most concerned".
Al Qaeda in the Land of the Islamic Maghreb has stepped up operations in North Africa since it changed its name from the Algerian Salafist Group for Prayer and Combat (GSPC) two years ago.
Whereas the GSPC focused on domestic issues, the new Al Qaeda offshoot has taken on an international agenda. In 2007 it bombed the UN's Algiers HQ, killing 41 people including 17 UN staffers.