Stradivarius stolen from US concertmaster

Milwaukee police are investigating the theft of a 300-year-old violin.

The rare Stradivarius violin was on loan to Milwaukee Symphony Orchestra concertmaster Frank Almond. The robber used a stun gun on Almond before taking the violin Monday night in a parking lot at Wisconsin Lutheran College,police said on Tuesday.

The instrument is the so-called Lipinski Stradivarius, crafted in 1715 The Milwaukee Journal Sentinel said.

In a 2008 newspaper story, Chicago violin dealer Stefan Hersh said the violin's value could be comparable to another Stradivarius that sold for more than $US3.5 million ($A4 million) in 2006.

The instrument was on indefinite loan to Almond from its anonymous owners. The violin's previous owners include virtuoso Giuseppe Tartini, who was known for his "Devil's Trill" Sonata, and Polish violinist Karol Lipinski.