Populist Italian politician Grillo swims Straits of Messina

MESSINA, Italy (Reuters) - Populist politician Beppe Grillo, the leader of Italy's second-largest party, launched a local election campaign in Sicily in colorful fashion on Wednesday by swimming the treacherous Straits of Messina that separate the island from mainland Italy.

Grillo's 5-Star Movement, capitalizing on a spate of scandals involving established parties, is the rising force of Italian politics and made spectacular gains in local elections in May, when it elected its mayor to the northern city of Parma.

It is hoping to make similar progress in the poorer south at a vote to renew Sicily's regional assembly on October 28.

Sixty-two-year-old Grillo, a shaggy haired former comedian who is renowned for his vitriolic diatribes against conventional politicians, swam the 3 km straits in just over an hour despite rain and stiff winds.

The Straits of Messina, which link the Tyrrhenian and Ionian seas below the toe of Italy's boot, are washed by strong currents and whirlpools which were personified in Greek mythology as two irresistible monsters, Scylla and Charybdis.

The 5-Star Movement, campaigning to clean up politics, break down monopolies and hold a referendum on Italy's euro membership, would win 20 percent of the vote according to opinion polls, the second largest share in the country's fragmented political landscape.

"The bookies were quoting me at 15 to 1, and were expecting I'd have a heart attack before half way," said a triumphant Grillo after completing the crossing.

(Reporting by Antonio Parrinello; Writing by Gavin Jones; Editing by Alison Williams)