Filed at 10:45 a.m. ET

WARSAW (Reuters) - Polish-born Colonel Ryszard Kuklinski, one of the United States' top Cold War spies, died in a Washington hospital Wednesday of a stroke, at the age of 74, local news agency PAP reported.

As a senior Polish military staff officer, Kuklinski passed some 35,000 top secret Warsaw Pact documents to the CIA between 1972 and 1981 before defecting with his family to the West.

``He was a tragic figure. On the one hand he was a Polish soldier, on the other an American spy,'' said Lech Walesa, former Solidarity leader and Poland's president after 1989.

``He did great things, risked his head when few of us would dare,'' Walesa told PAP.

A communist court sentenced Kuklinski to death in 1984 for passing intelligence to the United States, including communist authorities' plans to impose martial law in 1981 to crush Solidarity, the old Soviet bloc's first free trade union.

Poland overthrew communism in 1989, but the sentence on Kuklinski, who lived in Washington, was lifted only in 1995 and he was not rehabilitated fully until 1997.

He visited Poland in 1998 and received a hero's welcome by the then right-wing government, which said that thanks to people like Kuklinski the country had regained independence after five decades of Soviet-imposed regimes.

A CONTROVERSIAL FIGURE

But for many Poles Kuklinski was a controversial figure -- an opinion poll from the mid-1990s showed 34 percent thought he was a traitor and only 29 percent dubbed him a patriot.

Kuklinski's press agent said the colonel had hoped that his biography, ``A Secret Life,'' recently published in the U.S. by a New York Times journalist, would earn him respect among Poles.

``He believed that thanks to the book, his role will be fully explained and will earn him esteem,'' said Jerzy Bukowski.

Kuklinski joined the Polish army in 1947 soon after the Soviet Army imposed communism in Poland after World War II, and rose rapidly in his career.

But he grew appalled by the regime when the Polish army helped crush the Prague Spring in 1968 -- a bloody Russian-led military crackdown on Czechoslovakia's growing pro-democracy movement -- and when Polish soldiers were ordered to shoot at protesting shipyard workers in the city of Gdansk in 1970.

Kuklinski was survived by his wife. While he lived in hiding under an assumed name for many years in the United States, his two sons died in unexplained circumstances.

According to Polish newspaper reports, one son disappeared from a yacht which was later found by the U.S. coast guard. The other reportedly died in a car crash.