Known for his film music, he also waged a war of words and music against a military junta that banned his work and imprisoned him during its rule of Greece.

Mikis Theodorakis, the renowned Greek composer and Marxist firebrand who waged a war of words and music against an infamous military junta that imprisoned and exiled him as a revolutionary and banned his work a half century ago, died on Thursday at his home in central Athens. He was 96.

The cause was cardiopulmonary arrest, according to a statement on his website. His family said in a statement read on Greek state television that his body would lie in state, and Prime Minister Kyriakos Mitsotakis declared three days of national mourning.

Mr. Theodorakis was best known internationally for his scores for the films ''Zorba the Greek'' (1964), in which Anthony Quinn starred as an essence of tumultuous Greek ethnicity; ''Z'' (1969), Costa-Gavras's dark satire on the Greek junta; and ''Serpico'' (1973), Sidney Lumet's thriller starring Al Pacino as a New York City cop who goes undercover to expose police corruption.

In the early 1970s, Greek exiles were fond of sharing a story about an Athens policeman who walks his beat humming a banned Theodorakis song. Hearing it, a passer-by stops the policeman and says, ''Officer, I'm surprised that you are humming Theodorakis.'' Whereupon the officer arrests the man on a charge of listening to Theodorakis's music.

Contradictions were a way of life in Greece in the era of a junta that repressed thousands of political opponents during its rule, from 1967 to 1974. But to many Greeks, Mr. Theodorakis (pronounced thay-uh-doe-RAHK-is) was a metronome of resistance. While he was put away for his ideals, his forbidden rebellious music was a reminder to his people of freedoms that had been lost.

''Always I have lived with two sounds -- one political, one musical,'' he told The New York Times in 1970.

After he was released from a detention camp in 1970, he began an international campaign of concerts and contacts with world leaders that helped topple the regime in Athens four years later. It was a turning point for democracy, with a new constitution and a membership in the European Economic Community, which later became the European Union.

As Greece's most illustrious composer, Mr. Theodorakis wrote symphonies, operas, ballets, film scores, music for the stage, marches for protests and songs without borders -- an oeuvre of hundreds of classical and popular pieces that poured from his pen in good times and bad, even in the confines of drafty prison cells, squalid concentration camps and years of exile in a remote mountain hamlet.

He also wrote anthems of wartime resistance and socialist tone poems about the plight of workers and oppressed peoples. His most famous work on...