Former Soviet leader Mikhail Gorbachev on Friday traced the chill in Russia's relations with the West right to Washington's door.

Instead of ushering in a new era of cooperation with the West, the USSR's collapse — which Gorbachev himself helped bring about — put the United States into an aggressive, empire-building mood, the former leader said. Ultimately, he said, that has led the U.S. to commit a string of "major strategic mistakes."

"The idea of a new empire, of sole leadership, was born," Gorbachev told a packed news conference in Moscow. "Unilateral actions and wars followed," he added, saying that Washington "ignored the Security Council, international law and the will of their own people."

In the past Gorbachev has offered broad support for the policies of President Vladimir Putin, who is using Russia's oil driven economic strength to carve out a bigger role for Russia in global politics, but his criticism of the United States on Friday was especially harsh.

"The Americans want so much to be the winners. The fact that they are sick with this illness, this winners' complex, is the main reason why everything in the world is so confused and so complicated," he said.

Russia has fallen out with Washington on a raft of issues, pushing relations to a frosty state that some commentators have likened to the Cold War.

The Kremlin says the Bush administration's plans for a missile defense system in Eastern Europe could spark a new arms race. It has refused to back Washington's draft Security Council resolution on Kosovo's independence and has suspended its participation in a key treaty on arms reduction in Europe.

Gorbachev echoed Putin's frequent endorsement of a so-called "multipolar world," or one without the perceived dominance of the United States.

"No one, no single center, can today command the world. No single group of countries, like the G-8, can do it," Gorbachev said. "There is no option other than to build a multipolar world order, no matter how complicated this is."

That, he said, would not be achieved until the Bush administration had departed.

"Under the current U.S. president I don't think we can fundamentally change the situation as it is developing now," he said. "It is dangerous. The world is experiencing a period of growing global disarray."

Gorbachev backed Putin's proposal for a jointly run missile defense system and questioned who the U.S. was targeting, arguing that both Iran and North Korea were engaging with the West on their nuclear programs.

He also claimed that Putin's decision to suspend Russia's participation in the Conventional Forces in Europe Treaty was aimed at "encouraging" a dialogue on the amended version of the document which Russia has ratified but the United States and other NATO members have not.

Addressing the bitter diplomatic squabble with Britain over Russia's refusal to extradite a suspect in the polonium killing of former KGB agent Alexander Litvinenko, Gorbachev called for calm. The case has seen a tit-fot-tat expulsion of diplomats. "What's done is done — we need to stop and return to a dialogue and continue developing ties," he said.

Still, he said the case was "politicized" and, therefore, "someone needs it to be so, and to spoil relations." He said Britain "tries to be a good friend only for the United States."

Toasted in the West for ushering democratic reforms, Gorbachev is widely despised within the country for paving the way to the giddy economic free-for-all of the 1990s that brought fabulous wealth for a well-connected few, while plunging much of the country into humiliating poverty.

With parliamentary and presidential elections approaching, Gorbachev bemoaned the absence of a major liberal party in Russian politics, which is dominated by the pro-Kremlin United Russia. He dismissed Russia's main opposition group, Other Russia, as only "about making a bit of noise," and riding on the star power of its leader, former chess champion Garry Kasparov. "It's a very weak opposition," he said.

Speculation is rife over who will succeed Putin in next year's presidential election and what role he will play outside the Kremlin.

Gorbachev pitched in: "I am sure President Putin will find his place in future life. And this place will be a serious one. It will become clear very soon," he said.