GAZA CITY, Gaza Strip — Israel claimed a significant blow against Al Qaeda-inspired militants in the Gaza Strip on Sunday, killing one of the most influential leaders from an extreme branch of Islam that has targeted Egypt and Gaza’s Hamas rulers as well as Israel.

Hisham Saidani was killed alongside another top militant in the northern Gaza Strip in an air strike late Saturday, Israel’s military said. He was one of the main ideological guides for the violent, ultra-conservative ­Islamic movements in Gaza known as Salafi jihadis.