The Health Ministry has recorded two cases, including one death, in Nord-Ubangi province, bordering the Central African Republic.
The ministry said both patients were men in their 20s living in the Wapinda health zone, which borders Bas-Uele province, where Ebola cases have been reported previously.
Authorities have recorded at least 9,400 cases, including over 4,500 deaths, in the outbreak declared in mid-May, making it the deadliest in Congo's history.
The virus has spilled over into other countries including neighbouring Uganda, which has since declared itself free of the disease, and Kenya, which recorded a seventh case on Saturday. The Central African Republic has not recorded any confirmed cases.
"We see pockets of Ebola generally going down, but unfortunately geographically it's spreading out," World Health Organisation Regional Director for Africa Mohamed Yakub Janabi told The Associated Press in an interview in Beni, eastern Congo, on Friday.
Janabi said one of the biggest challenges has been convincing those who are infected to seek medical assistance, adding that some deaths occur in the community outside of health centres.
Nord-Ubangi is located between Sud-Ubangi and Bas-Uele, the last two provinces the disease had spread to along the border with the Central African Republic, where recurring armed violence has forced thousands to flee and take refuge in Congolese border communities. Access in the region can be difficult due to poor roads and limited communication networks.
Ituri province in eastern Congo remains the disease's epicentre, accounting for almost three quarters of confirmed cases, according to the government's most recent data, which shows 66 health zones have been affected since the start of the outbreak.
Congo's state-news agency ACP reported on Sunday that authorities in North Kivu province - where WHO says substantial transmission continues - will introduce a one-week ban from Monday on people entering the province from Ituri in an effort to slow the spread of the virus.
Other measures that will be introduced include prohibiting carrying more than two people on a motorcycle or four people in a car, as well as suspending big public gatherings such as at mass sports activities, nightclubs and political demonstrations.
The spread of the outbreak, caused by the rare Bundibugyo virus for which there is no approved vaccine or treatment, is fuelled by mass population movements, rebel violence, mistrust and poor working conditions of front line workers.
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