RAFAH, Gaza Strip - Israel and the Palestinian Authority today said they fear al-Qaida terrorists will infiltrate into Gaza through the open Gaza-Egypt border, where Palestinians and Egyptians have been crossing largely unfettered since Israel withdrew from the area four days ago.

In a deal worked out with Israel, Egypt is supposed to deploy 750 border troops to secure the frontier and prevent weapons smuggling, but neither those troops nor Palestinian policemen have been able to halt the flow of people and arms, including hundreds of assault rifles and pistols.

Israel fears international terrorists will exploit the chaotic border to infiltrate Gaza and Israel.

"We're talking about Iran, we're talking elements in Syria, we're talking about groups like Hezbollah and we're talking also about international terrorist groups like al-Qaida," said Israeli foreign ministry spokesman Mark Regev.

Rafiq Husseini, the top aide to Palestinian leader Mahmoud Abbas, said, "we are even more worried than Israel about al-Qaida coming here because al-Qaida will harm us more than Israel." Such a presence, he said, would hurt prospects for peace and renewed negotiations with Israel.

Al-Qaida has been active in northern Egypt but there has been no indication they've infiltrated Gaza, which until this week has been tightly sealed.

Senior Israeli military officials said they feared al-Qaida operatives could enter Gaza from Sinai and connect with the local Hamas militant group to share expertise and provide weapons.

Regev and other officials said Israel fears that militants will leave Gaza and enter Israel through the Egypt-Israeli border in the Sinai Desert, an unfenced frontier. The Egypt-Israel border has long been a favorite crossing point for drug runners, illegal workers and prostitutes.