A United Nations relief official says the Gaza Strip could soon face economic disaster if the Hamas-run Palestinian territory remains sealed off.

The deputy head of the U.N. Relief and Works Agency (UNRWA), Filippo Grandi, says Gaza risks becoming 100 percent dependent on foreign aid within weeks. He was speaking Thursday at a news conference in Gaza City.

Israel and Egypt closed their trade crossings with Gaza to all but humanitarian aid after Hamas militants seized the coastal strip in June in fighting with the rival Fatah party.

In other news, Egyptian officials say the last major group of Palestinians stranded in Egypt since Hamas took control of Gaza have now returned to the territory.

The officials say about 400 Palestinians crossed from the Sinai Peninsula into Israel via the Nitzana border terminal before continuing on to Gaza.

The Palestinians were unable to enter Gaza directly because the Rafah border was shut after the Hamas takeover.

The closure of Rafah initially stranded 6,000 Palestinians in Sinai, where many had complained of poor living conditions.

About 30 Palestinians have refused to return to Gaza via Israel, saying they fear arrest by Israeli authorities. Egyptian authorities are holding the group at the El Arish airport in Sinai.

Also Thursday, Hamas militants arrested a senior Fatah health official in Gaza. Hamas fired Dr. Jomma Saka from his post at Gaza's main Shifa hospital Wednesday, prompting a two-hour strike by hospital workers.

Some information for this report was provided by AFP, AP and Reuters.