MOSCOW — Alexander Yakovlev, who spearheaded former Soviet President Mikhail Gorbachev's political reforms of openness known as glasnost and boldly exposed Communist crimes, died Tuesday. He was 81.

Yakovlev died at his home in Moscow of an unspecified illness, said Oleg Pivovarov, a spokesman for the politician's International Democracy Foundation. Yakovlev suffered from high blood pressure and earlier in the day had visited the Kremlin Clinical Hospital, Pivovarov said.

As Gorbachev's right-hand man, Yakovlev championed reforms that eroded the Communist Party's tight grip on political life and liberalized Soviet society.

Gorbachev called Yakovlev's death an "irreparable loss."

"He made an enormous contribution to the democratic processes and the transformation of the country," said Gorbachev, who was on a trip to London, according to the ITAR-Tass news agency.

Yakovlev, born in the village of Korolyovo in the Volga River Yaroslavl region, fought in the Red Army in World War II and was badly wounded in 1943. He graduated from the history faculty of Yaroslavl University and became a Communist Party apparatchik.

He rose through the ranks, but was sent to Canada after a falling out with other members of the party's leadership and served as Soviet ambassador from 1973-83. It was there that he had a fateful first meeting with Gorbachev in 1982, when the future leader was a visiting member of the Communist Party's ruling Politburo.

It was an electric encounter of like-minded men, Yakovlev recalled in a 1995 interview with The Associated Press.

"We were in an open field waiting for the arrival of an official," Yakovlev reminisced. "We discussed everything, we interrupted each other and said 'That thing must be changed and that one's intolerable ... everything's intolerable.'"

After Gorbachev became Soviet leader in 1985, he quickly named Yakovlev to key party posts. In 1987, Yakovlev became the full member of the Politburo in charge of ideology.

As a senior adviser to Gorbachev, Yakovlev played a key role in encouraging media freedom. He fended off attacks from a die-hard wing of the Communist Party that fumed at news reports exposing Soviet dictator Josef Stalin's purges and other Communist crimes.