Anti-aircraft Hawk and Italian Spada missile batteries were deployed on the outskirts of the Italian capital as Rome's airspace closed down along with the city's two secondary airports, Ciampino and Urbe, where many dignitaries are to land to attend Friday's funeral.

Italy's aviation authorities said Thursday air traffic to Rome's main Fiumicino airport would drop 30 percent by Friday.

Private planes were already barred from flying over the Italian capital as of Wednesday, as police helicopters hovered over the Vatican.

Italian Interior Minister Beppe Pisanu said the security operation "has no precedents in history."

NATO also joined the operation, deploying AWACS surveillance planes and F-16 fighter jets that are to patrol the skies over the capital non-stop, being refueled in the air by a Boeing 707, Italian media reported.

If a small plane were to get past the tight security net, missile-armed helicopters would be ready to shoot it down, reports said.

Road traffic throughout the city and its outskirts will also be barred from 2:00 am (0000 GMT) Friday until at least 6:00 pm, officials said, in a first in modern Roman history.

But scheduled and special trains would continue to arrive and buses would be allowed to park in 4,000 designated areas on the outskirts.

While the number of city buses and metro trains servicing the Vatican increased sharply Rome St. Peter's railway station, closest to the tiny state, will remain closed until Friday midnight (2200 GMT).

Up to 1,000 sharpshooters were to be deployed for the funeral in strategic points in Rome, many of them behind the statues that top the colonnades of Saint Peter's Square, daily La Repubblica reported.

In all, more than 10,000 security forces, more than 8,000 volunteers from throughout Italy and 20,000 members of the municipal staff will be involved in the operation to protect both the dignitaries and multitude that has reached Rome from all over the world over the past few days.

Police, soldiers and Italy's paramilitary Carabinieri worked overtime to control the crowds in the Vatican neighborhood, where tens of thousands continued to queue to see the body of the Polish-born pontiff lying in state at St. Peter's Basilica.

Volunteers handed out 800,000 litres of free bottled water to pilgrims Wednesday and expected the number to reach nearly two million by late Friday.

Units with explosive-sniffing dogs also patrolled the area, and Rome's Prefect Achille Serra appealed to pilgrims planning to attend the outdoor funeral at the square not to bring bags or backpacks to ease the work of security forces.

Serra insisted authorities had the "unprecedented" situation under control, adding that public offices would also be closed Friday along with schools.

Shops were asked to give employees a day off so they can stay at home.

He said the shutdown was ordered "to guarantee security and avoid a day of complete confusion."

"This does not mean Rome is in a state of emergency," Serra added.

Security measures faced their first test Wednesday evening with the arrival of US President George W. Bush, who immediately went to the Vatican to pay his last respects to John Paul II.

Italian President Carlo Azeglio Ciampi was briefed Thursday on the preparations for the funeral by Guido Bertolaso, the country's commissioner in charge of measures in Rome.

Ciampi was particularly worried that rain could further complicate preparations for Friday, but weather forecasters said rain was only expected Friday afternoon, with temperatures hovering around 17 degrees Celsius.

The funeral is to start at 10:00 am (0800 GMT).

The requiem mass can be followed on 27 giant screens set up across the city, of which six alone on the avenue leading up to Saint Peter's.

Asked whether he was worried about the security situation Italy's interior minister said: "I think the pope will continue to give us a helping hand."

John Paul II died Saturday following years of ill health.

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