JERUSALEM, Aug. 26 (Xinhua) -- The Israeli who sailed to the Gaza Strip with other international activists in defiance of an Israel-imposed sea blockade was released "conditionally" Tuesday evening after being questioned, local news service Ynet reported.

    Sderot Police Chief Shimon Nachmani was quoted as saying that The Israeli, Prof. Jeff Halper, "was held for questioning and the decision whether to arrest him will be taken at the end of the probe."

    Halper was interrogated at a border crossing in the afternoon on his way back from the Palestinian enclave, before police put him into custody at a police station in the southern town of Sderot, Angela Godfrey-Goldstein, a contact person for the protest organizer Free Gaza Movement, told Xinhua.

    She said that Halper, the only Israeli participant in the voyage, was arrested for violating the law prohibiting Jewish citizens from entering the coastal strip.

    The incident took place two days after Halper and some 40 other activists with the U.S.-based group reached the Gazan coast in a mission they said aimed to break the siege the Jewish state has imposed upon the Hamas-ruled area.

    Before giving the so-called "one-time" green light for the two boats, Israeli government had warned that such a provocative move "constitutes the legitimization of a terrorist organization" and that all options would be considered.

    Israel tightened its restrictions on the Palestinian region since Hamas, a group Israel blacklists as a terrorist organization, seized control of the area last year from the long-dominant Fatah faction. The land border, sea and air of the strip are currently all under Israeli control.