Ivory Coast closed its border with Ghana Friday, after at least eight people were killed in attacks on its security forces launched from the neighbor's territory.

Ivory Coast's officials say the attacks took place Thursday and Friday in the commercial city of Abidjan and the border town of Noe. They said land, air and sea borders with Ghana will remain closed until further notice.

Ivorian authorities believe that supporters of former President Laurent Gbagbo are behind the attacks, which are raising fears of renewed instability a year after a post-election civil war killed more than 3,000 people in the west African country. The long-time ruler refused to concede election victory to his opponent Alassane Ouattara.

Ghana's President John Dramani Mahama has said that Ghanaian territory would not be used as a base for operations aimed at destabilizing its neighbor.