ROME, June 12 (Reuters) - A whirlwind ploughed through islands and villages in the lagoon surrounding Venice on Tuesday, tearing roofs off homes and uprooting trees but leaving the city's historic centre unscathed, Italy's civil protection agency said.

Pictures and amateur videos of the late-morning storm were quickly posted on Italian Web sites. They showed a thick, dark column rising behind the city's belltowers and cupolas, which were not damaged.

The island of Sant'Erasmo, located near the mouth of the channel that leads from the lagoon to the Adriatic sea, was the hardest hit, firefighters reported.

Many of Sant'Erasmo's homes were left without roofs, and firefighters laid tarps to keep rain out of the damaged homes. Numerous trees were toppled and farmland was damaged in the wind and rain.

Only one minor injury was reported.

The twister then moved northeast, causing damage in the towns of Cavallino, Jesolo and Eraclea, a civil protection spokeswoman said.

In Italy, thin water spouts are often spotted snaking over the sea, and whirlwinds are sometimes seen over land, but large, damaging tornadoes like those associated with the United States are rare. (Reporting by Steve Scherer; Editing by Roger Atwood)