MOSCOW -- Nikolai Ryzhkov, a former Soviet prime minister who presided over botched efforts to shore up the crumbling national economy in the final years of the USSR, has died. He was 94.

During his six-year tenure, Ryzhkov worked to implement Soviet leader Mikhail Gorbachev's liberal reforms that lifted rigid centralized controls and encouraged private initiatives, but failed to adapt to the quickly changing economic and political environment, setting the stage for the 1991 Soviet collapse.

Ryzhkov's death was announced Wednesday by Valentina Matviyenko, the speaker of the upper house of Russian parliament where he served until October and was the oldest member. She didn't name the cause of death or immediately announce funeral arrangements.

Ryzhkov, who was born to a coal miner's family in the Donetsk region of then Soviet Ukraine, underwent training as a mechanic and in 1950 was sent to work at the Uralmashzavod in the Urals, one of the main Soviet industrial enterprises.

After two decades of working at the plant, he was named its director and in the following years rose swiftly through the ranks of Soviet hierarchy to get senior posts at the ministry of heavy industries and the Gosplan state planning agency, before being named the head of the economics department of the Communist Party's Central Committee.

Quickly after coming to power in 1985, Gorbachev put Ryzhkov in charge of implementing his "Perestroika" modernization effort as the country's prime minister.

As part of Gorbachev's reforms, Soviet authorities offered industrial plants and farms more freedom in their economic activities and also lifted restrictions on private entrepreneurship, resulting in quick growth of the private sector.

In 1990, Ryzhkov announced a price liberalization program that was intended to overcome the deficit of some staples and help fill the shelves. The effort didn't work as planned, resulting in galloping inflation and exacerbating food shortages that fueled public anger.

Amid Gorbachev's political reforms that led to the creation of democratic opposition to the Communist Party, Ryzhkov faced scathing criticism for his performance in the national parliament where he was once derided as a "crying Bolshevik" after speaking nervously during a heated argument with critics.

Ryzhkov was relieved of his duties in January 1991 after suffering a heart attack.

He left politics after the breakup of the USSR, but returned to Russia's political scene in 1995 when he was elected to the lower house of parliament, where he served until 2003 before moving to the upper house. Like most other members of the Kremlin-controlled parliament, Ryzhkov supported President Vladimir Putin's policies.