ROME - Italy officially celebrated its 150th anniversary as a unified state Thursday, with dozens of world leaders attending the ceremony rarely seen in recent years.

Italy's President Giorgio Napolitano (R) shakes hands with Chinese Vice President Xi Jinping (L) at Fori Imperiali during a military parade to celebrate Italy's 150th anniversary of unification, in Rome June 2, 2011. [Photo/Agencies]

Chinese Vice President Xi Jinping, Russian President Dmitry Medvadev, US Vice President Joe Biden, and Argentinean President Cristina Fernandez were among the world leaders in Rome Thursday for a massive military parade that started in front of Rome's Coliseum and which included demonstrations of Italy's most advanced military hardware and several pass-overs from supersonic jets.

The June 2nd is actually the anniversary of the constitutional referendum that created the modern Italian republic in 1946. The actual date of Italian unification is March 17, 1861- 150 years and six weeks ago - when the Kingdom of Italy was formed. But that anniversary passed with relatively low profile celebrations this year, amid bickering between key members of Berlusconi's government.

The June 2nd national holiday, always a larger celebration in Italy, revealed none of the political infighting that has become more apparent in recent weeks.

Umberto Bossi, head of the Northern League, the second largest political party in the ruling government coalition, was conspicuously silent Thursday  only days after he predicted the local election results from Monday could hasten the end of his party's collaboration with Italian Premier Berlusconi's followers.

A few anti-Berlusconi protesters gathered in parts of the center, but they failed to attract much attention. And the parade route through Rome's historical center  starting at the Coliseum, and winding around Piazza Venezia before finishing at the fields of Circus Maximus  attracted large and enthusiastic crowds.

But political commentators say the peace is unlikely to last long. Bossi's allies in parliament have called a press conference for next week in which they are expected to lay out new demands in return for their continued support of the Berlusconi government. And the polling firm Opinioni reported Thursday that early indications were that, despite all the positive images associated with Thursday's celebrations that Berlusconi's approval levels did not benefit much.

After a short hiatus, two of Berlusconi's three court cases are set to restart before mid-June, guaranteeing another round of negative publicity.

"The visiting leaders and the feel good imagery from an event like the one Thursday is all good politics for the government," Maria Rossi, Opinioni's co-director, told Xinhua. "But with the depth of problems this government has, it is probably best to look at it as a welcome respite from all the troubles but not anything that will establish a new tone going forward," she said.