The alert came after the World Health Organization (WHO) confirmed a link between a fatality in Liberia, months after it was declared Ebola-free, and new cases in its neighbour Guinea.
A woman died of Ebola in the Liberian capital Monrovia on March 31, after arriving from Guinea, where a fresh Ebola outbreak has killed eight of the nine cases registered since mid-March.
Two of her three children, aged five and two, have since tested positive for the virus.
“Our findings were that everything was in place and we are keeping a constant health watch on both pedestrian and vehicular traffic entering and leaving,” he said after returning from a visit to the Guinea border.
The WHO said on Thursday it had “established epidemiological links between new Ebola cases in Liberia and a current flare-up of Ebola in neighbouring Guinea following intensified case investigations and contact tracing”.
Liberia was the country worst hit by the outbreak of the disease which has claimed 11 300 lives since December 2013, the vast majority in Liberia, Guinea and Sierra Leone.