VATICAN CITY- The Christmas Eve attack on Pope Benedict XVI highlighted the headache of providing watertight security for the leader of the Roman Catholic Church without cutting him off completely from his flock.

Italian-Swiss national Susanna Maiolo, 25, stunned pilgrims during the Christmas Eve mass at St Peter's Basilica by leaping over a security barricade and dragging Pope Benedict, 82, to the floor.

The pontiff quickly recovered and went on to celebrate mass.

But French Cardinal Paul Poupard, who was with Benedict at the time of the assault, said afterwards the incident was "definitely a threat" to the pope and that security should have been tighter.

"With hindsight, you would say greater vigilance was needed, so those in charge of security should not let their guard drop even for a second," the cardinal said on RTL radio, though he acknowledged the difficulty of the task.

"You can go over everything with a fine-tooth comb, (but) if someone really wants to do harm, they will do it -- you can never have a 100 percent guarantee of stopping them," he added.

Vatican spokesman Federico Lombardi played down Thursday's incident, praising Pope Benedict's "great self-control and control of the situation," he said."It was an assault, but it wasn't dangerous because she wasn't armed."

Lombardi said the only way to protect the pope from all risk would be to create a wall between him and the faithful, but that this was "unthinkable."

Pope Benedict has faced down attempted assaults and terrorist threats in the past -- most recently last Christmas when the same woman, Maiolo, tried to grab him before being restrained by bodyguards.

In June 2007, a 27-year-old German man jumped the security barrier and boarded the popemobile as it passed before a crowd in St Peter's Square.

The Holy See dramatically reinforced security around the pope after Mehmet Ali Agca, a Turk, shot and nearly killed Benedict's predecessor John Paul II in St Peter's Square in May 1981.

The Al-Qaeda extremist network has repeatedly threatened to kill Pope Benedict, accusing him of being anti-Islamic.

Such threats -- against the pontiff and the Catholic Church -- have seen airport-style security introduced in Vatican City in recent years.

The midnight Christmas mass is already one of the few occasions when members of the public can get close to the pope.

Enrico Marinelli, a former head of the Vatican police force, said over-zealous personal protection would make the pontiff's job more difficult.

"Having full security around the head of the Catholic Church could limit his pastoral activity," he said.

The Vatican rarely releases details on the pope's security arrangements, but he is understood to have some 350 officials responsible for protecting him.

They include 110 members of the Pontifical Swiss Guard, 140 Italian police officers and 100 officers from the Vatican's own police service.

St Peter's Square is now encircled by metal barriers, and pilgrims must pass through security checks and metal detectors before entering the basilica.

Italian police regularly patrol the area, which is monitored by closed-circuit television. At busy times of year, snipers take up positions on surrounding rooftops and sniffer dogs are deployed to detect explosives.

Helicopters, armored cars, all-terrain vehicles and ambulances are also provided in busy periods.