A first batch of 4,000 inoculations has arrived in the capital Kinshasa, with another 4,000 to follow soon after.
The spread of the deadly virus from the countryside and into a city that is home to about a million people pushes the current outbreak into a "new phase", essentially making the efforts to contain the outbreak far harder.
The outbreak was first spotted in the Bikoro zone, which has 31 of the cases and 274 contacts.
Kalenga added that the authorities were tracing all air, river, and road routes in and out of the city in order to trace the source of the virus.
Before Wednesday's announcement, there had been only two cases of the virus confirmed by lab tests.
The announcement came just as thousands of doses of the experimental Ebola vaccine arrived in the country, with vaccinations expected to commence this coming weekend.
The vaccine, developed by Merck and Co Inc, is still not licensed but proved effective during limited trials in West Africa in the biggest-ever outbreak of Ebola, which killed 11,300 people in Guinea, Liberia and Sierra Leone from 2014 to 2016.
Ilunga says the ministry has recorded 42 cases of hemorrhagic fever in Congo's remote northwest.
MSF and its research arm Epicentre are also working closely with the Congolese Ministry of Health and the World Health Organization (WHO) on the implementation of the Ebola vaccine rVSVDG-ZEBOV-GP as an additional measure to control the outbreak.
The WHO said it had sent 300 body bags for safe burials in affected communities.
Out of the 20 persons died in DRC, 3 are health workers, Director of the Center John Nkengasong said.
The vaccine is complicated to use, requiring storage at a temperature between -60 and -80 degrees Celsius.