North Korea is suspected of producing biological weapons to unleash against enemy troops and civilians — including by fake janitors lugging backpack sprayers containing deadly pathogens, according to a report.

“North Korea is likely to use biological weapons before or at the beginning of a conflict to disrupt society and create panic, incapacitate societies, and/or cause a significant military diversion,” according to the Belfer Center for Science and International Affairs at the Harvard Kennedy School.

Dictator Kim Jung Un’s rogue regime plans to spread the pathogens through various means such as missiles, drones, aircraft and even portable sprayers, the report said.

“It is theoretically possible that North Korean sleeper agents disguised as cleaning and disinfection personnel could disperse (biological weapons) agents with backpack sprayers,” the report said.

The biological weapons also may be unleashed by the 200,000 special-forces troops, the Korea Herald reported.

The Belfer Center says the hermit kingdom is producing the biological weapons in facilities disguised as agricultural research labs.

“It is likely that anthrax and smallpox is already used as a biological weapon,” the report said. “North Korean soldiers are vaccinated against smallpox, and so are US Army (personnel) stationed in South Korea — against smallpox and anthrax.”

North Korea has 13 types of biological agents that it can weaponize within 10 days, according to the report, which cites a 2015 South Korean Defense Ministry parliamentary audit.

Anthrax and smallpox are the likely agents it would deploy “in bioterrorism or in an all-out war,” according to the report. Others pathogens include the plague, cholera and botulism.

“Agents like anthrax could cause mass casualties with a small amount: only a few kilograms of anthrax, equivalent to a few bottles of wine, released into a dense city could kill 50 percent of the population,” the report said.

“If used on a large scale, these weapons can cause not only tens of thousands of deaths, but also create panic and paralyze societies.”

It is not known whether North Korea has the capability of weaponizing all 13 types of agents, the researchers said.

The report added that the difficulty in verifying North Korea’s capabilities arises in part from the mixed use of the equipment and facilities in creating the weapons.

“While nuclear programs can be monitored by the number of nuclear tests and the success of missile tests, weaponizing and cultivating pathogens can stay invisible behind closed doors,” the authors said.

“Moreover, equipment used for (biological weapons) production are often dual-use for agriculture, making external monitoring and verification virtually impossible.”

Meanwhile, North Korea threatened the US with an “unimaginable” nuclear strike for conducting military exercises with South Korea in the waters off the Korean Peninsula.

“The US is running amok by introducing under our nose the targets we have set as primary ones,” warned the state-run Korean Central News Agency, Newsweek reports. “The US should expect that it would face an unimaginable strike at an unimaginable time.”

Japanese Defense Minister Itsunori Odonera warned that the North’s missile capabilities have grown to an “unprecedented, critical and imminent” level.

“Therefore, we have to take calibrated and different responses to meet that level of threat,” he said.