JERUSALEM (JTA) -- Palestinian rival factions Fatah and Hamas in a formal ceremony signed a unity agreement, repairing a four-year rift.

The ceremony Wednesday in Cairo was delayed for two hours after a question about whether the head of the Islamist Hamas, Khaled Meshaal, should sit on stage and if he would speak at the event.

The signing of the unity deal turns "the black page of division," Palestinian Authority President Mahmoud Abbas, the head of the Fatah party, said following the signing at the Egyptian intelligence headquarters.

Most air traffic in Israel resumed Friday morning using emergency jet fuel supplies after the discovery Thursday of contaminated jet fuel at airports throughout the country. It forced the shutdown of all airplane refueling at Ben-Gurion Airport, causing the cancelation of scores of flights.

Terrorism and sabotage were both ruled out, according to media reports.

When air traffic resumed Friday morning, planes were loaded with enough fuel to allow them to fly to Cyprus or Jordan, where they were then loaded with enough fuel for their scheduled trip.