"The number of nominations increases almost every year, which shows a growing interest in the prize," the head of the institute, Geir Lundestad, told AFP.
The Nobel committee convened Tuesday for the first time this year to examine the candidate list and will announce the laureate in Oslo on October 10th. As usual, the committee refused to reveal the identity of any of the nominees, but Lundestad said that 47 of the 278 candidates were organizations.
Even though the list is kept secret for at least 50 years, the sponsors can choose to reveal the name of their nominee.
Putin is thought to be on the list, since Russian figures proposed his name in October, citing his role in the Syrian crisis. The former KGB agent is credited with averting a US attack against Syria by suggesting putting Bashar al-Assad's regime's chemical weapons arsenal under international control.
Being nominated for the Nobel Peace Prize is relatively easy, since thousands of people can suggest candidates: lawmakers and ministers, university professors and former laureates. At their first meeting, the five committee members themselves can add more names to the list. The committee insists that being nominated does not imply an endorsement on its part.
Putin's chances of winning the prize appear limited given the ongoing crisis in Ukraine.
Malala still on the list
Another name likely to be on the list is Edward Snowden, former US security contractor for the National Security Agency, who has been provided asylum in Russia and is accused in his country of disclosing a large number of classified documents regarding a US global surveillance programme. Other figures with a similar profile, such as Julian Assange -- founder of WikiLeaks -- and Chelsea Manning are also known to be on the list.
Pakistani 16-year-old Malala Yousafzai, who was seriously wounded when she was shot in the head by a Taliban gunman at point blank range for promoting girls' education in Pakistan, is again known to be nominated, after being considered one of the favourites last year.
However, the prize went to the Organization for the Prohibition of Chemical Weapons (OPCW), involved to this day in the dismantling of the Syrian chemical weapons arsenal.
Other names known to be on the list include jailed Belarussian rights activist Ales Belyatski and Denis Mukwege, a pioneering doctor who founded a clinic for rape victims in the Democratic Republic of Congo, both nominated in the past.
Kristian Berg Harpviken, director of the Peace Research Institute Oslo (PRIO) and one of the few experts to speculate openly on the winner, said his favourite for this year was Pope Francis for his efforts to redistribute wealth in the world.
Asked about the situation in Ukraine, Berg Harpviken said it was difficult to point out an individual or an organisation that could play a major role in the region in the months to come.
"The dramatic situation in which Ukraine finds itself could influence the Nobel committee's thoughts, but at this stage I don't see any clear candidates standing out," he said.
Other leads point at the peace processes in Burma and Colombia, which could deserve a Nobel prize if there were a major breakthrough in the next months.