"We have agreed to take important and extraordinary actions at the inter-country level to focus on cross-border regions that have more than 70 percent of the epidemic," said Hadja Saran Darab, the secretary-general of the Mano River Union bloc grouping the West African nations.
"These areas will be isolated by police and military. The people in these areas being isolated will be provided with material support," Darab added.
The announcement came at the end of an emergency summit, also attended by Ivory Coast and the World Health Organization, to launch a USD 100 million response to an epidemic which has killed more 700 people.
"Burials will be done in accordance with national health regulations. We agreed to provide our health personnel with incentives, treatment and protection so they could come back to work."
Darab did not outline the exact area to be part of the isolation zone, but the epicentre of the outbreak spreads from Kenema in eastern Sierra Leone to Macenta in southern Guinea, almost 300 kilometres (185 miles) away.