(Reuters) - An anonymous donor on Friday offered to pay a $100,000 reward for information leading to the safe return of a Stradivarius worth millions of dollars stolen from a Wisconsin concert violinist, the Milwaukee Symphony Orchestra said.

The 300-year-old Stradivarius was stolen from violinist Frank Almond on Monday night by thieves who shot the musician with an electric stun gun after he had completed a performance with the instrument in suburban Milwaukee.

"We are hopeful that this reward will aid in the recovery of this priceless treasure so that it may be enjoyed by Milwaukee's cultural community and the international arts world for years to come," Mark Niehaus, the orchestra's president and executive director, said in a statement.

The donor, who wishes to remain anonymous, is offering the $100,000 to anyone who can provide information that results in the safe return of the stolen Stradivarius, an orchestra spokeswoman said.

The so-called Lipinski Stradivarius, an instrument made in 1715, can be distinguished by unique striations on its back. Its anonymous owner had loaned the violin indefinitely to Almond.

The missing instrument is one of roughly 600 violins, violas and cellos built by the famed Italian artisan Antonio Stradivari that are still in existence.

A similar Stradivarius violin sold at auction for $2.3 million in December, according to the BBC.