Rare recordings by famous visiting classical musicians broadcast in the 1950s and ’60s, including a performance by cellist Mstislav Rostropovich on his first trip to Japan, have been found in the archives of Tokyo Broadcasting System Holdings Inc.

The broadcaster said Tuesday that the 218 monaural but high-quality pieces also include a performance by cellist Pablo Casals on his first visit to Japan in 1961 and the last concert given by violinist Jascha Heifetz in 1954.

The recordings were found in the course of digitizing analog tapes stored in the TBS archives. Some of them will be broadcast by Ottava, an Internet classical music station run by TBS, starting at 6 p.m. Sept. 15.

The recordings were originally aired by Radio Tokyo, the precursor to TBS, during programs including “Hyakuman nin no Ongaku” (“Music For a Million People”), a classical music show that began with the station’s 1951 founding.