Hamas leader in exile Khalid Mash'al arrived in Cairo Sunday night as head of a delegation from his Islamist party, Al-Jazeera reported, ahead of a meeting with President Mahmoud Abbas who arrived in the Egyptian capital earlier in the week.

The two are expected to sign a historic unity document and set of guiding implementation principals that will reunify the governments of the West Bank and Gaza Strip.

Abbas and Mash'al, along with their respective delegations, will meet Monday for a series of talks ahead of the signing.

An Al-Jazeera report also noted that Mash'al would meet with officials in Cairo about ways to alleviate the humanitarian conditions in the coastal enclave. On Thursday, Egyptian officials announced that the Rafah crossing would be permanently opened. The opening is expected to commence in less than two weeks.

Palestinian factions will also gather in Cairo for the meetings, with the Popular Front for the Liberation of Palestine to be represented by a delegation headed by its Deputy Secretary-General Abd Ar-Rahman Mallouh.

In a statement, PFLP said its delegation was "going to Cairo with all determination to bring about the success" of a unity agreement, adding that it was in "full support of the efforts by Egypt and the Arab League to end division."

Rebuilding Gaza, the statement added, should be a top priority for the new technocrat government set to be charged with arranging elections in the next year.