TEL AVIV ø Israel has appealed to its nationals to leave Egypt immediately and authorities increased the alert level in the Jewish state amid intelligence that strikes were being planned following the bombing of two vacation sites packed with Israelis.

Officials said the alert has been compounded by the refusal of Egyptian authorities to cooperate in the search and rescue effort in Taba.

Officials said that for nearly nine hours, Egyptian authorities prevented Israeli medical and rescue teams from crossing the border in Sinai, Middle East Newsline reported. They said that even after permission was granted by the regime of President Hosni Mubarak, Egyptian police continued to block the entry of Israeli heavy equipment and crews to search for those trapped in the rubble of the Taba hotel.

"There are efforts to evacuate the Israeli injured," Brig. Gen. Ruth Yaron, the Israeli military's spokeswoman, said on Friday. "We will need Egypt's permission for a helicopter to get a full picture of the situation. Unfortunately, the Egyptians haven't granted this permission. We are having difficulties in getting a range of approvals."

The massive nearly-simultaneous attacks on Israeli targets in Egypt have been attributed to Al Qaida.

"This appears to be the work of international terror groups such as Al Qaida or its branches," Israeli Deputy Defense Minister Zeev Boim said. "It is not the kind of attack that we know comes from Palestinian terror organizations."

Two vacation sites packed with Israelis were bombed on late Thursday in Egypt's Sinai Peninsula. One target was the Taba Hilton Hotel, near the southern Israeli port of Eilat. A beach packed with Israelis was bombed farther south along the Sinai coast.

At least 26 people were said to have been killed and more than 120 injured in the two attacks. Twenty-four of the casualties ø including seven Egyptians ø were reported in Taba. Officials said nearly 30 people believed to have been in the hotel were missing.

Officials said the Taba hotel was destroyed in two nearly simultaneous bombings. They said a car bomb exploded outside the hotel and a woman suicide bomber blew herself up in the lobby.

Less than 30 minutes later, at least two Israelis were killed and more than 15 were injured in two car bombings in Ras Al Shitan near the resort town of Nueiba, located 40 kilometers south of Taba. The beach targeted was filled with Israeli vacationers.

Two Islamic insurgency groups claimed responsibility for the attacks. One of the claims came from Gamiat Islamiya Alamiya, or World Islamist Group, and the group warned of future attacks. Gamiat was said to be aligned to Al Qaida.

Another group that claimed responsibility for the strikes in Sinai was the Union of Islamic Brigades. The group, believed linked to Al Qaida, praised Osama Bin Laden in a communique posted on the Internet. Both Gamiat and the Union of Islamic Brigades said they were avenging Israeli strikes against Hamas in the Gaza Strip.

"They [attackers] could have been Al Qaida or the military wing of Hamas," Ehud Yatom, a senior member of the Knesset Foreign Affairs and Defense Committee, said.

For the last month, Israeli authorities had been on alert for a massive Islamic strike on Israel. Israel had warned its nationals not to travel to Egypt's Sinai Peninsula because of information of plans by Islamic insurgents to attack Israeli tourists.