By Antonio Denti and Cristiano Corvino
VENICE (Reuters) - U.S. actor George Clooney and Lebanese-born human rights lawyer Amal Alamuddin formalized their marriage in a civil ceremony in Venice on Monday, capping star-studded weekend nuptials.
The two, who married at a lavish party on Saturday night, spent about 10 minutes inside the lagoon city's 14th century city hall for a civil service registering their marriage.
It was presided over by former Rome mayor and close friend, Walter Veltroni.
Alamuddin, 36, wore a white trouser suit with a crop top and a wide-brimmed white hat with a black ribbon. The 53-year-old Clooney, dubbed until now as the world's most famous bachelor, wore a light gray suit.
The couple arrived and left aboard the speedboat water taxi "Amore" they have used all weekend. They waved and smiled at photographers in other boats and well-wishers on bridges along the Grand Canal.
The brief service ended the single status of the two-time Oscar winner who several years ago reportedly made a $100,000 bet with actress Michelle Pfeiffer that he would never remarry after his 1993 divorce from actress Talia Balsam.
Alamuddin, and the Kentucky-born Clooney, who shot to stardom in the television series "ER", have been the toast of Venice's canals and palaces since Friday, when they arrived for four days of festivities.
The couple, along with A-list stars such as actors Matt Damon and Bill Murray, singer Bono, Vogue editor Anna Wintour and model Cindy Crawford, have been shuttling between luxury hotels, turning Venice into a Hollywood on the Adriatic.
Alamuddin has represented Ukrainian former Prime Minister Yulia Tymoshenko at the European Court of Human Rights, and WikiLeaks founder Julian Assange in extradition proceedings.
Her family left Lebanon during the 1975-1990 civil war to settle in Britain, and she has also advised former United Nations Secretary General Kofi Annan on the conflict in Syria, an issue about which Clooney has spoken publicly.
Clooney has also led campaigns to highlight the plight of refugees in Darfur, Sudan, and is expected to donate the fees earned from selling rights to the wedding photos to that cause.
Alamuddin was rumored to have prepared 12 outfits for the long weekend, during which guests were ferried around the city in speedboats bearing flags marked "AG", for Amal and George.
(Additional reporting by Philip Pullella; Editing by Louise Ireland)