Russian leader Vladimir Putin has trumped US President Barack Obama as the most powerful man in the world, while German Chancellor Angela Merkel retains her title as the world's most powerful woman, according to a yearly ranking published by Forbes magazine on Wednesday (30 October).

With his signature healthcare legislation under fire, allies outraged over spying and a barely-averted default on US debt, Obama can no longer be seen as the most powerful man in the world, Forbes editors write.

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"It appears that President Obama's lame duck period has set in earlier than usual for a two-term president, causing him to drop one notch from the No. 1 spot," they add.

Meanwhile, the ex-KGB strongman is solidifying his power in Russia "and anyone watching the chess match over Syria has a clear idea of the shift in the power towards Putin on the global stage."

With the possibility of prolonging his presidency until 2024 and with a tight control over the country's oil and gas reserves, Putin has little to worry about when confronted with European or US criticism about human rights in his country.

One of his louder critics, but also the leader of a country with lucrative business relations with Russia, is Germany's Merkel - who for the eighth time in the past 10 years is awarded the title of the "most powerful woman in the world."

"The world's most powerful woman is the backbone of the 28-member European Union and carries the fate of the euro on her shoulders. Fresh off a commanding reelection in September 2013, she has served as ­Chancellor of Germany since 2005 - the first woman in the position," Forbes writes.

Merkel has also climbed in the male-dominated "most powerful people in the world" to the fifth spot, just after Pope Francis and the Chinese leader, Xi Jinping.

Mario Draghi, the head of the European Central Bank, is number nine on that list, followed by UK Prime Minister David Cameron (11) and French President Francois Hollande (18).

Apart from Draghi, no other EU official made it to the 72-strong list.

As for the female ranking, former French finance minister Christine Lagarde, currently head of the International Monetary Fund, is deemed the seventh-most powerful woman in the world. The Queen of the UK ranks 40, after pop stars such Beyonce and Angelina Jolie.

Forbes also did a ranking of the world's top billionaires.

The third richest man in the world is Spain's Armancio Ortega, who owns 60 percent of clothing brand Zara. His wealth is estimated at €41.5 billion. Forbes also notes that he bought valuable properties in Spain "at bargain prices" when the economy collapsed.

The richest man in the world is Microsoft founder Bill Gates (€52 billion), followed by Mexican telecoms chief Carlos Slim Helu (€50 billion).