OSLO (AFP) - The names of the Nobel laureates often elicit surprise when they are revealed, but last-minute predictions that hit the bull's-eye have sparked suspicions of leaks by the institutes that hand out the awards.

Last week, US President Barack Obama clinched the prestigious Peace Prize and German writer Herta Mueller won the Literature Prize, surprising most observers -- except for a handful of journalists and punters who correctly predicted them as the laureates.

When Obama's name was read out at the Nobel Institute in Oslo on Friday, a collective gasp went through the room.

And yet, on the eve of the announcement, Norwegian commercial television TV2 had suggested he was the most likely winner.

"I wasn't 100 percent sure, but for me, Obama was the most logical choice. I'm surprised that others were surprised," Gerhard Helskog, the TV2 journalist behind the news clip, told AFP.

He insisted Obama's name was not leaked to him. He explained he had simply tried to think like the Nobel committee and worked "a little with sources," providing no other details.

His good thinking was not immediately rewarded though.

"After my news clip aired, a lot of people wrote to me on Twitter to tell me I was an idiot," he said.

Enlightened punters also bet on Obama, who saw his odds drop from 33-to-1 to 18-to-1 on www.paddypower.com -- until the site suspended betting on the US leader's name just hours before Friday's announcement because of the site's "sizable liability."

The Nobel Institute in Oslo has always denied any leaks, and even the list of nominees remains secret for 50 years.

Officially, only the five members of the Nobel committee and its influential secretary Geir Lundestad are privy to the laureate's name, with Lundestad once admitting that he never even shared the secret with his wife.

That leaves the media to engage in a frenzied guessing game in the run-up to the announcement.

Public broadcaster NRK has the best record in recent years: in 2003 and 2004, it correctly predicted the until-then unknown names of Shirin Ebadi, an Iranian human rights advocate, and Kenyan environmentalist Wangari Maathai.

And last year, one of its reporters was standing outside Finnish troubleshooter Martti Ahtisaari's door at the time of the peace prize announcement.

But it missed the target this year.

"Generally, we base our work on clues and sources but this time around we didn't succeed in putting together the pieces of the puzzle," the head of NRK's foreign news service, Stein Bjoentegaard, told AFP.

In Stockholm where the other Nobel prizes are announced, the same suspicions arise regularly, in particular for the Literature Prize.

After correctly predicting French author Jean-Marie Gustave Le Clezio last year, Sweden's paper of reference Dagens Nyheter hit the nail on the head again by devoting the front page of its cultural section to Mueller on Wednesday, the day before the announcement.

Cultural editor Maria Schottenius denied the name was leaked to her.

"No, if we had been tipped off we couldn't have run with it the way we did (on the front page). Leaks have to be handled discreetly," she told Dagens Nyheter.

The Swedish Academy which awards the prize also ruled out a leak.

Its administrative director Odd Zschiedrich told AFP it was "an educated guess," and said Mueller had been seen in the media as a "strong candidate for many years."

After Dagens Nyheter's article, Mueller's odds plunged on online betting site Ladbrokes, where she ended up in second place behind Israel's Amos Oz.

Stephen Farran-Lee, editor at Swedish publishing house Bonniers who had also predicted Mueller, said the annual guessing game was easier if one follows the Academy closely.

He noted that Mueller's name was mentioned last year after the Nobel committee was seen attending a seminar on her work at a book fair, and that the same thing happened in previous years for laureates Imre Kertesz and Elfriede Jelinek.

"The members of the Academy are only human. You can't ask them to put on fake noses when they go out. If you're industrious enough and follow their interests and movements, one can easily enough figure out who's in line for the prize," he said.