Israeli authorities kept the Kerem Shalom crossing closed for a fifth day on Monday, after imposing a closure last week following rocket fire from Gaza.Israel closed the Gaza commercial crossing on Thursday after a rocket was fired at southern Israel and reduced the fishing zone around Gaza from 6 to 3 miles.The zone had been extended to 11 km as part of an Egyptian-brokered ceasefire that ended an eight-day conflict between Israel and Hamas in November, in which 166 Palestinians and six Israelis were killed.Magles Shoura al-Mujahedeen, a hardline Islamist Salafi faction with a small presence in Gaza and the neighboring Egyptian Sinai, claimed responsibility for the rocket salvo on Sderot last week.The crossing will likely be opened after upcoming Jewish religious holidays, Palestinian sources said.