Labboune, Lebanon: Fabio Carlone says his small, lightly armoured, Puma vehicle is just the right size for patrolling the narrow, potholed lanes of southern Lebanon.

The flaw, however, is that the vehicle provides little protection against the kind of car bomb that killed six of his United Nations colleagues last month. And Master Corporal Carlone says that weighs on his mind every time he and his Italian comrades go out on patrol along the Lebanese-Israeli border.

The UN Interim Force in Lebanon (Unifil) was increased from 2,000 to 13,300 peacekeepers after the month-long war last summer between Israel and Hezbollah. The UN peacekeepers are led by elite European troops and are charged with helping the Lebanese Army ensure that the tense border remained calm.

But a year on, Unifil still finds itself under threat, not from the Shiite Hezbollah, but from suspected radical Sunni militants possibly inspired by Al Qaida. And in a bizarre twist, some Unifil contingents are now seeking the cooperation of the powerful Hezbollah, which also views militant Sunnis as a threat, to help provide tacit security for the peacekeepers, Hezbollah and Unifil sources say.

Last month, six Spanish and Colombian soldiers serving with Unifil's Spanish battalion were killed when a car bomb exploded beside their armoured vehicle, the deadliest attack in Unifil's 29-year history.

Last week, a Unifil jeep was damaged when a small bomb exploded nearby, confirming fears that last month's bombing was not a random act.

"We are facing threats, but not threats about our ability to carry out our mission," says Maj. Gen. Claudio Graziano, Unifil's commander, at his headquarters in the southern coastal village of Naqoura.

As Lebanon's political crisis intensified in the wake of the war last summer, Unifil began receiving increased intelligence warnings of potential attacks by Al Qaida-inspired militants.

Ayman Al Zawahiri, Al Qaida's deputy leader, twice referred to Unifil in video-taped messages, describing the peacekeepers as "international crusader forces." The growing threat of attack by Sunni radicals apparently spurred the leading European troop-contributing states to seek Hezbollah's cooperation.

According to Unifil sources, intelligence agents from Italy, France, and Spain met with Hezbollah representatives in the southern city of Sidon in April. As a result, some Spanish peacekeepers subsequently were "escorted" on some of their patrols by Hezbollah members in civilian vehicles, the Unifil sources say.

A day after the six peacekeepers were killed last month, Spanish foreign minister Miguel Angel Moratinos spoke with Manucher Mottaki, the foreign minister of Iran, Hezbollah's main patron. According to a Hezbollah official in south Lebanon, there has been at least one meeting between the Shiite party and Spanish Unifil officers since the bombing.