ACCRA, Ghana — Ivory Coast officials say that fighters who backed former president Laurent Gbagbo have infiltrated refugee camps in Ghana and are accused of attacking security bases back in Ivory Coast.

Human rights groups say the presence of Gbagbo's ex-fighters in the camps poses a threat to the security of refugees.

An official of Ghana's Refugee Board said some fighters had slipped into the three refugee camps housing Ivorians.

In one example, Ghanaian authorities in May lost track of nearly 150 suspected fighters who were supposed to be transferred to a maximum security prison and now their whereabouts are unknown.

Ivorian President Alassane Ouattara's government alleges that Gbagbo's fighters have attacked military positions in Ivory Coast. Since early August, about 10 such attacks have been carried out throughout the country.