The Italian government has sent its chief antiterrorist fighter to Sardinia to deal with a rash of kidnapings that has terrorized wealthy visitors to that Mediterranean island.

The move to send in Carabiniere Gen. Carlo Alberto Dalla Chiesa came Tuesday following news of the kidnaping of two of Italy's best-known folk singers, Fabrizio de Andre and Dori Ghezzi, a former winner of the San Remo song festival.

The couple disappeared from their farm in northern Sardinia early Tuesday, bringing to 12 the number of people kidnaped in Sardinia since July 7. Kidnaping for ransom has become common in Italy in recent years. But 13 of this year's 40 kidnapings have occurred in Sardinia where this form of banditry has historical roots.

The De Andre-Ghezzi kidnaping came one week after the disappearance in Sardinia of British businessman Rolf Schild, his wife, Daphne, and their daughter, Annabelle, 15. A group calling itself "Red Guerrilla" claimed responsibility for the Schild kidnapings.

Also kidnapped in Sardinia last week were the two teen-age children of a wealthy Piedmontese banker, and another northern industrialist. On July 7, the wife and daughter of a Milanese businessman were seized in the first of the unprecedented multiple kidnapings. A young married couple kidnaped a few days later are alone among the recent victims to have been released, reportedly for a ransom more than $1 million. Ten people, including De Andre and Ghezzi, are still prisoners.

The decision to send Gen. Dalla Chiesa into the antikidnaping battle was taken as an indication of Premier Francesco Cossiga's concern. Dalla Chiesa's special mandate and command of crack antiterrorist who, himself a Sardinian, returned to Rome today after a 10-day vacation on the island.

Regular police and Carabinieri units in Sardinia also have been reinforced.Following the discovery of Ghezzi's automobile in the port city of Olbia today, police in Genoa and Civitavecchia questioned thousands of passengers disembarking from ferries arriving from the island.