By Sara Rossi

MILAN, June 24 (Reuters) - A celebrity wedding party for Amazon founder Jeff Bezos and journalist Lauren Sanchez in Venice this week has been moved to an isolated, less accessible part of the lagoon city on security concerns and to prevent the risk of protests, sources said.

The billionaire tech-tycoon and his fiancee had earmarked a location in Cannaregio to celebrate after their marriage, a popular and central nightlife area, but fears of demonstrations led to a change of plan, the sources added.

For weeks some local residents and pressure groups have been complaining that the event will turn the scenic city of gondolas and palazzi into a private amusement park for the rich, and threatened peaceful blockades.

After the wedding ceremony, whose location and exact date remain secret, although it is expected to be between Thursday and Saturday, some 200-250 VIP guests from show business, politics and finance will now head to a hall of the Arsenale, a vast 14th-century complex in the eastern Castello district.

Surrounded by water and impossible to reach by land when connecting bridges are raised, the hall is considered a safer venue than Cannaregio's Scuola Grande della Misericordia, a medieval former religious school.

Originally a giant shipyard serving the Venetian Republic's maritime empire, the Arsenale has been restored and converted into an exhibition space for the Venice Biennale art fair.

Bezos, 61, executive chair of e-commerce giant Amazon and no. 4 on Forbes' billionaires list, got engaged to Sanchez, 55, in 2023, four years after the collapse of his 25-year marriage to Mackenzie Scott.

The couple's decision to marry in Venice follows other celebrity weddings in the floating city, such as that of U.S. actor George Clooney and human rights lawyer Amal Alamuddin in 2014.

"The news that Bezos has run away from the Misericordia is a great victory for us," said Tommaso Cacciari, a leader of the "No Space for Bezos" campaign that is leading the anti-wedding front.

The group has announced more protests for Saturday on Venice's canals, bridges and narrow streets, pledging to make the event a "nightmare" for Bezos and his guests.

Luca Zaia, president of the Veneto region that comprises the city, criticised the protests, saying the 90 private jets carrying guests to nearby airports would bring revenue of up to 48 million euros ($55.69 million) to local businesses.

U.S. President Donald Trump's daughter Ivanka and son-in-law Jared Kushner, who have been holidaying in Tuscany, visited the factory of luxury sports car maker Ferrari on their way to the Venice wedding, a source familiar with their movements said.

($1 = 0.8618 euros)

(additional reporting by Giulio Piovaccari in Milan, writing by Gavin Jones and Alvise Armellini, editing by Alexandra Hudson)

((gavin.jones@thomsonreuters.com; +39 06 8522 4232;))