Egyptian police have questioned the head of the Khan Younis police patrol after he was arrested at the Rafah crossing on his return from Egypt on Thursday, where his father has been undergoing medical treatment, a security official has confimed. "A Hamas-affiliated police officer, Ibrahim Marouf, was detained for his involvement in a number of disturbances against Egyptian security forces on the Gaza border," the official said. He added that Marouf remained under investigation in the port city of Al-Arish and "would be transferred to Cairo for further questioning." Marouf's father was allowed to re-enter Gaza. The number of Palestinians in Egyptian custody has now risen to 23, and includes the leader of the Hamas arm Al-Qassam Brigades, Ayman Nofal, who was arrested two years ago. An Egyptian border guard was killed in December when he was shot by a Hamas sniper during a demonstration on the Egyptian border against the construction of an underground steel fence to stop smuggling to and from the Israeli-blocked Gaza Strip.