"Investigations are ongoing to identify the source of transmission and the line-listing of contacts," the ministry reported.
This message comes months after the end of a two-year outbreak that killed roughly 11,300 people. The outbreak was declared over in May 2015, after spreading across Liberia, Guinea and Sierra Leone.
Liberia closed its borders with neighboring Guinea and Sierra Leone after new announcements of Ebola in March. This measure is now seen to have failed to prevent the spread of the virus.
In March, Russia claimed it obtained the legal basis to test a recently-developed Ebola virus vaccine. According to reports, 2,000 Guinea citizens are to be vaccinated during the test.