Protesters on about 20 boats confronted police in the lagoon in front of Venice's main square before a meeting of the Italian and French leaders.

Police vessels blocked the protest boats from approaching the lagoon banks at St. Mark's Square with water cannons while another group protested on land. Both groups dispersed a short time later.

More than 500 demonstrators turned out Tuesday to protest plans to restart work on the long-delayed Lyon-Turin high-speed train line, as well as the presence of big cruise ships in the fragile Venetian lagoon.

Italian Premier Matteo Renzi and French President Francois Hollande are expected to discuss Libya and the migrant crisis during a meeting dedicated to Venice native Valeria Solesin, the only Italian killed in the Paris attacks on Nov. 13.