L'Aquila, Italy  - He ducked and he dived, he charmed and he chided, he smiled and, most importantly of all, he survived.

Silvio Berlusconi, arguably the most controversial leader to have ever presided over a Group of Eight (G8) summit of the world's most powerful nations, entered this year's get-together in L'Aquila with the reputation of a gaff-prone lecher.

He emerged from it with the aura of a consummate diplomat, skilfully steering heads of state and government from the four corners of the planet to a compromise on monumentally complex issues such as climate change and trade liberalization.

The crooner-turned-billionaire-turned-politician also won praise for organizing a summit in the space of less than three months - the meeting was moved from its original venue in Sardinia to L'Aquila weeks after the April 6 earthquake that devastated the central Italian city.

He even orchestrated a historic handshake between Libya's rogue leader, Moamer Gaddafi, and US President Barack Obama.

"We have just concluded the final session of what has been a highly productive summit here in L'Aquila," Obama said after attending his first G8 as president.

"And before I discuss what we've achieved these past three days, I'd like to take a moment to express my thanks to Prime Minister Berlusconi, his staff, the people of Italy for their extraordinary hospitality and hard work in setting up this summit," Obama said.

According to John Kirton, a professor of political science from Canada who has followed every G8 since 1988, Berlusconi "lived up to expectations."

Above all, "he didn't screw it up," said Kirton, whose Toronto- based G8 Research Group gave the summit a positive B+- grade.

That Kirton should say so speaks volumes of the prejudices that accompany Italy's maverick prime minister - many of them justified.

In the days preceding the summit, both the national and international media had a ball reporting about the 72-year-old's alleged involvement with female minors and call-girls.

Those reports largely eclipsed any talk of the numerous corruption charges that had been levelled against him in the past, or of the numerous slips of the tongue that have turned him into the least diplomatic premier in the Western world.

Analysts say there were two key elements to this success.

The first was to limit his exposure to the artillery of scandal- mongering journalists. The owner of three television networks and of at least as many newspapers and magazines avoided taking any questions on the first day of the summit and only took those from friendly media outlets on the second.

When a journalist from La Repubblica - the left-of-centre daily that mounted a fierce credibility campaign against him - took the microphone, he cut him short.

The second, and far more important reason for Berlusconi's accomplishment, is Obama.

European leaders and experts alike were near-unanimous in pointing to the new US president as the man responsible for the summit's success.

Among them Berlusconi himself.

"There's a great change in US policy compared to the previous administration that turned their back on this problem. Instead, Obama has decided to be at the helm of this movement," Berlusconi said when asked about the deal that was reached to fight global warming.

"It is very important that (Obama) is now showing leadership on important issues" and continues to do so, said Swedish Prime Minister Fredrik Reinfeldt, current holder of the European Union's rotating presidency.

Such views were shared by both Kirton and Maurizio Caprara, a diplomatic correspondent for Italy's highly respected daily Corriere della Sera.

"This summit demonstrated Obama's power to shape the world," Caprara said, pointing to the US president's fundamental role in reaching consensus in L'Aquila.

Ironically for a man who counts George W Bush a personal friend, the person Berlusconi has to thank for his success in L'Aquila is the man who has turned Bush's policies on their head.(dpa)