The Islamic State West Africa Province (ISWAP) insurgent group in Nigeria has claimed responsibility for a series of attacks on Nigerian military bases in Borno State over the past week, which reportedly killed dozens of soldiers.

In a statement released by Amaq News Agency, an outlet affiliated with ISIS, the group said it carried out the attacks last week.

Some Nigerian media outlets had already reported parts of these attacks, although the number of soldiers killed varies from ISWAP’s claims.

In an unusual development, the group also acknowledged the deaths of several of its own fighters during clashes with security forces.

ISWAP further claimed that it attacked four military bases in a single night, an operation it said resulted in multiple soldier fatalities.