US whistle-blower and former spy agency contractor Edward Snowden is among the top candidates for the 2016 Nobel Peace Prize which is awarded in Oslo, Norway.

"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 in Oslo told Reuters, putting him on top of his list of candidates.

In the wake of Snowden's leaks of details of the US government's spy programs, many countries have been reforming laws to restrict surveillance programs, helping human rights, Harpviken said.

Snowden began leaking classified intelligence documents in June 2013, revealing the extent of the NSA’s spying activities, including the massive collections of phone records of Americans and foreign nationals as well as political leaders around the world.

The US government has filed espionage charges against Snowden, who has been granted asylum in Russia.

An award of the $930,000 prize to Snowden would be a huge snub by NATO member Norway to US President Barack Obama, the 2009 Nobel Peace laureate.

However, the award to Obama was widely criticized in the United States and the rest of the world. It came just nine months after Obama became president.

Harpviken said US Energy Secretary Ernest Moniz and Ali Akbar Salehi, the head of Iran’s Atomic Energy Organization, had the second best chance of winning for their role in negotiating a nuclear deal with Iran last year.

"Huge numbers of nominations are still coming in," said Olav Njoelstad, director of the Norwegian Nobel Institute. The committee will have its first meeting on February 29 and announce the winner in October.