Former US spy agency contractor Edward Snowden, peace negotiators in Colombia and Greek islanders helping Syrian refugees are among those favoured for the 2016 Nobel Peace Prize, with the deadline for nominations looming.

Nobel watchers on Monday also speculated that negotiators of an accord over Iran’s nuclear program could be in the running after a surprise award last year to a coalition of Tunisian democracy campaigners, the National Dialogue Quartet.

“2016 may finally be Edward Snowden’s year … His leaks are now having a positive effect,” Kristian Berg Harpviken, head of the Peace Research Institute, Oslo, told Reuters on Monday, putting him top of his list of candidates.

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Harpviken said many nations were now reforming laws to restrict intelligence gathering, helping human rights, in the wake of Snowden’s leaks in 2013 of details of the US government’s surveillance programs.

Washington has filed espionage charges against Snowden, who has been granted asylum in Russia.

An award of the $US930,000 ($A1.31 million) prize to Snowden, by a Nobel committee in NATO member Norway, would be a huge snub for President Barack Obama, the 2009 Nobel laureate.

Asle Sveen, an historian and expert on the prize, said he thinks the “obvious choice” for 2016 would be to honour Colombia’s government and FARC rebel group — if they succeed in peace talks launched in 2012 to end five decades of war.

He noted Norway’s government had been involved in organising peace talks, perhaps swaying the five-member Norwegian Nobel committee which is appointed by parliament.

Other candidates include Greek islanders who have helped Syrian and other refugees — a campaign by grassroots group Avaaz has collected 635,000 online signatures for a prize to islanders who “have opened their homes and hearts”.

February 1 is the annual deadline for nominations.