A senior member of the Hamas movement politburo, Imad el-Alami, previously based in Syria, returned to the Gaza Strip on Sunday.
Hamas sources said he was the last remaining member of the movement's Damascus-based politburo to leave Syria.
Hamas decided to leave Syria in order not to be seen as endorsing the regime of President Bashar Assad in his bloody crackdown against his own people.
El-Alami crossed into Gaza on Sunday night through the Rafah crossing, between the Hamas-ruled coastal enclave and Egypt. Leaders and supporters of Hamas gathered at the border crossing and received him with chants and cheers.
In 1991, Israel deported el-Alami, originally from the Gaza Strip, to south Lebanon.
Three years ago, el-Alami settled in Syria, together with Khaled Meshal, the chief of the movement's politburo. Before moving to Syria, he had been Hamas's ambassador in Tehran.
Hamas has never officially announced its intention to move its headquarters from Damascus. Sami Abu Zuhri, Hamas' spokesman in Gaza, told reporters that Al-Alami came to Gaza for a visit, but he refused to say how long he intended to stay.
Earlier on Sunday, Israeli Radio reported that el-Alami had been the contact person between Hamas militants in the West Bank and those in the Gaza Strip.
Abu Zuhri denied that there were regional guarantees for the return of el-Alami to the Gaza Strip, adding that "a Palestinian who is coming home doesn't need guarantees."
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