Israel has protested to Egypt over the opening of a border crossing to allow Muslim pilgrims from Gaza to make their way through Egypt to Saudi Arabia.
Some 2,000 pilgrims have crossed the border to go on the Hajj
The Israelis say they are concerned that militants may leave Gaza and go for training in Iran.
Gaza has been largely sealed off since June, when Hamas took control in Gaza. Some 2,000 Palestinians are said to have left Gaza via Rafah since Monday.
The Rafah crossing is the only exit from Gaza that bypasses Israel.
It is the first time Palestinians in Gaza have been allowed to cross directly into Egypt since June.
Israel has only allowed small numbers of residents to pass through its territory and into Egypt for humanitarian reasons.
An Israeli foreign ministry official said Israel had "conveyed its displeasure and concern to Egypt" about the opening of the Rafah crossing.
Hamas leader Ismail Haniya, who served as Palestinian Authority prime minister in a national unity government before he was dismissed by President Mahmoud Abbas of Fatah, praised Egypt's actions.
"Egypt opened its heart and arms and allowed the opportunity to prove that the ties of nationalism, Arabism and Islam prevail, and allowed our pilgrims to pass through Egypt," he said.
The pilgrimage, or Hajj, to the Islamic holy places in modern-day Saudi Arabia is a religious duty for all able-bodied Muslims.