The Islamic State's branch in Egypt has claimed responsibility for a wave of deadly attacks that killed 15 Egyptian soldiers and three civilians the previous day in volatile northern Sinai.

A statement posted Friday on a militant website associated with the group, known as "Sinai Province," says its fighters attacked seven checkpoints, killing "dozens of soldiers" on a main road in the Sinai Peninsula leading to the border with Gaza Strip.

Egyptian authorities said 15 soldiers were killed and 19 were wounded in an attack on a checkpoint on Thursday south of the town of Sheikh Zuweyid. Three civilians died in near-simultaneous attacks elsewhere in Sinai, suggesting careful planning by the militants.

The attacks were the latest in a series of large-scale assaults by the Sinai-based militant branch.