DEIR KIFA, Lebanon - U.N. troops sent to keep the peace in southern Lebanon are taking strong defensive measures against possible suicide attacks — worried because al-Qaida has warned they are considered enemies of Islam.

The peacekeepers are putting up checkpoints and picking remote spots for their bases. French soldiers, for instance, plan to set up one of their main bases in Baraachit, on a plateau that is more than 2,600 feet high.

France is taking no chances in light of an earlier aborted peacekeeping mission in Lebanon. It pulled out of that operation after a suicide truck bombing in Beirut killed 58 French soldiers on Oct. 23, 1983 — the same day a similar attack killed 241 U.S. Marines.

"For us, the protection of the force is the top priority because it could be a target for an attack by al-Qaida or another group," French Col. Olivier de Cevins said at his temporary headquarters near Deir Kifa, a town 12 miles from the Israeli border.

U.N. troops face a difficult mission in guarding against a resumption of the Israel-Hezbollah war and helping the Lebanese army re-establish government control in the south, a longtime stronghold of Hezbollah's militant Shiite Muslims.

Yet despite tensions as Hezbollah faces U.N. restrictions on arms shipments, and even though Hezbollah was blamed for the 1983 attacks, many European peacekeepers do not see that group as the primary threat.

"I am more concerned about a group that is foreign to the Lebanese, such as al-Qaida, than about Hezbollah," the head of the Spanish military contingent, Col. Luis Melendez, said in an interview last week with the Spanish newspaper El Pais.

In a video message released on the eve of the fifth anniversary of the Sept. 11 attacks, al-Qaida's No. 2, Ayman al-Zawahri, condemned the presence in Lebanon of U.N. peacekeepers "who are hostile to Islam."

He singled out the "French crusaders," announcing a "blessed union" with an Algerian insurgent group to target France.

Lebanon's acting interior minister, Ahmed Fatfat, who already had warned al-Qaida was trying to establish itself in Lebanon, told The Associated Press that al-Zawahri is "trying to profit" from the current instability.

"There is always a risk. We are in a difficult part of the world. That is why we are working together to manage the problem and defend the U.N. forces," he said.

Although al-Qaida has rarely carried out attacks in Lebanon, it is believed to have sympathizers among extremist factions in Palestinian refugee camps.

In December, al-Qaida in Iraq claimed responsibility for a rocket attack into northern Israel apparently carried out by a radical Palestinian group.

Fatfat said Lebanese authorities had broken up four al-Qaida cells this year. The biggest bust was in January when police arrested 13 people believed linked to al-Qaida — seven Syrians, three Lebanese, one Saudi, a Jordanian and one Palestinian — on suspicion of planning attacks.

But Lebanese authorities are reluctant to intervene in the largest Palestinian refugee camp, Ein el-Hilweh, where al-Qaida affiliate Asbat al-Ansar is believed to have people.

The 15,000 foreign soldiers who will deploy in an 18-mile-deep strip of territory on Lebanon's southern border with Israel represent a potentially soft target.

At the entrance to an access road leading toward the camp housing Spain's 500-man contingent in Taibe, five Spanish marines with automatic weapons backed up by an armored personnel carrier stood watch on one recent day.

At a second checkpoint 500 yards away, soldiers gestured urgently for a vehicle to slow down. After radioing headquarters and a 15-minute wait, they took down ID details and the vehicle registration, and allowed the car to proceed with an escort inside.

Yet, despite their worries about terror attacks, the U.N. troops don't want to be seen as occupying forces, so some Spanish troops carry out patrols on foot wearing no body armor or helmets.

The French rear base near Deir Kifa that will house off-duty soldiers lies just off a public road. But French military officials say they don't want to set up checkpoints on the road because that would alienate residents.

Rohan Gunaratna, a leading terrorism expert at Singapore's Institute of Defense and Strategic Studies, said the U.N. force faces a significant terror risk.

"I think that the peacekeeping forces must be prepared to suffer casualties. It is the most challenging peacekeeping mission that the international community has embarked on for a long time," he told AP by telephone from Singapore.

On the other hand, the Shiite fighters of Hezbollah may not welcome an incursion into its heartland by the Sunni Muslims of al-Qaida.

But Gunaratna said it's not inconceivable that Hezbollah's patrons — Syria and Iran — might allow terror strikes by Sunni radicals to pressure nations to withdraw their peacekeepers.

De Cevins, the French officer, said all possible measures will be taken to minimize risks. In particular, troops will be dispersed rather than housed in a single building as was the case with the French and Marine barracks targeted in 1983.

"You will never 100 percent avoid an attack. But we expect that we wouldn't suffer such big losses if one did happen," he said. (AP)