Cameroon has restricted movement along its border with Equatorial Guinea following "several unexplained deaths" from an unknown illness that causes hemorrhagic fever, Health Minister Malachie Manaouda said on Friday.

The restrictions were imposed in view of "the high risk of importation of this disease and in order to detect and respond to any cases at an early stage", he said in a statement.

Investigations are underway and epidemiological surveillance has been strengthened with the support of experts from the World Health Organization (WHO) and the Atlanta Centers for Disease Control and Prevention.

"At the current stage... there is no reason to be worried," Malachie said.

Equatorial Guinea said in a statement on Wednesday that it had registered an "unusual epidemiological situation" over the past weeks in its Nsok Nsomo district, Kie-Ntem province, that caused nine deaths in two adjacent communities over a short space of time.

A crisis commission set up by the health ministry reported a tenth death on Thursday.

The symptoms observed were fever, weakness, vomiting blood and diarrhea.

A team was sent to isolate contact cases and take samples that were sent to a regional WHO lab for testing. A woman and her two children were taken to hospital, where they recovered after receiving mild treatment, the statement added.

A WHO spokesperson said the agency was supporting the testing of samples to identify what has caused the deaths, and should get results within the coming days.

Cameroon said around 20 deaths had been recorded on Wednesday in villages in Equatorial Guinea's Kie-Ntem province, which borders Cameroon's Olamze district.

The symptoms of the "non-identified illness" were nose bleeds, fever, joint pain and other ailments that caused death within a few hours, the head of health for the district, Ngu Fankam Roland, said in a statement.

He told Reuters on Friday that no cases had been detected or suspected in Cameroon so far.