A new case of Ebola emerged in Liberia on Friday in a setback for the country declared free of the disease on September 3 and for the region, which is struggling to end an epidemic that has killed around 11,300 people.

The patient is a 10-year-old boy who lived with his parents and three siblings in Paynesville, a suburb east of the capital Monrovia, said Minister of Health Minister Bernice Dahn.

All six family members, as well as other high risk contacts, were in care at an Ebola Treatment Unit in Paynesville, Dahn said.

"The hospital is currently decontaminating the unit. All of the healthcare workers who came in contact with the patient have been notified," she said told a news conference.

"We know how Ebola spreads and we know to stop Ebola but we must remain vigilant and work together," she said.

Bruce Aylward, who leads the Ebola response for the UN World Health Organization, said the patient had no history of contact with an Ebola survivor or victim.

"The family obviously is at particular risk and are being investigated right now because two of the siblings have been unwell over the last two days so they are also being investigated," he told a news conference in Geneva.

Liberia has seen more than 10,600 cases of the disease and 4,808 Ebola deaths since it was first announced in March, 2014, according to WHO figures.

The virus has killed about 11,300 people in Guinea, Sierra Leone and Liberia, but Sierra Leone was declared free of the virus on Nov. 7 and Guinea has begun its countdown to the end of the virus.

The 42-day countdown to be declared Ebola-free starts when the last patient tests negative a second time, normally after a 48-hour gap following their first negative test.