Anti-aircraft rocket launchers are in place around Rome, and a navy warship armed with torpedoes is patrolling the coastline near the capital, as Italian authorities stepped up its security measures with almost 20,000 police and volunteers ahead of Pope John Paul II's funeral.

According to Italian officials on Thursday, some 200 top political leaders and royals from around the world are expected to attend Friday's funeral, while huge crowds of pilgrims flocking to Rome for the funeral will double the population of the city.

The city of Rome was doing a great job in meeting the funeral's security and organizational problems, and the European Union was impressed by the way Italy had risen to the challenge, officials said.

Rome Mayor Walter Veltroni said the city had outdone itself in coping with the biggest mass gathering ever.

"The situation is under control," said Veltroni, adding that Roman citizens have done their bit to give officials a helping hand with the unprecedented arrivals.

Massimo Fogari, a spokesman for the Defense Ministry, said anti-aircraft missiles were already in place around the capital. But he refused to give a specific number and the location of the rockets.

Italy's air force will be ready to scramble fighter jets during the funeral, and snipers will take up positions on rooftops, he added.

Additional measures include intensified armed patrols on the Tiber River that flows through Rome and a no-fly zone with an 8-km radius over the city of Rome during the funeral.

Although Italian authorities are playing down the threat of a possible terrorist attack, an official admitted that "it's obvious that we would be naive to underestimate such a large-scale event and the possibility of a crazy guy causing problems."

"The current international situation and the number of people in the piazza call for measures of great attention," he said, adding that authorities have no indications of a terrorist plot in the making.

Interior Minister Giuseppe Pisanu has met with Italian police commanders and the chief of the domestic intelligence service on a plan "to guarantee the best conditions of security" for the funeral, the ministry said in a statement.