Incoming president Rodrigo Duterte will restart peace negotiations with communist rebels in the third week of July, the two sides said on Thursday in Oslo after two days of informal talks.

A previous round of talks to end decades of conflict with the National Democratic Front (NDF), an umbrella group controlled by the communists, collapsed in 2013.

But the recently elected Duterte had campaigned on ending the conflict.

Jesus Dureza, Duterte's peace adviser, said the talks would resume after the new tough talking president takes office on June 30.

"We will recommend the release of all political prisoners to Duterte once he assumes the presidency and both sides will work for an interim ceasefire to boost the formal resumption of peace talks in the third week of July in Oslo," Dureza told reporters in the Norwegian capital.

Previous talks under outgoing President Benigno Aquino collapsed after he refused a rebel demand to release imprisoned members.

Negotiators in Norway said the two sides agreed to discuss granting amnesty for political prisoners, establishing an interim ceasefire and setting a timeline for talks.

Duterte's negotiators also said the government had agreed to have some detained rebels play a role in the peace talks, meeting a key demand of the communists.

More than 500 political prisoners are being held, including 19 members of the rebels' negotiating team.

Agreeing to the talks is likely to be the start of a long and difficult process, but Dureza said the two sides were "very optimistic" the talks would succeed.

Duterte has agreed to appoint two leftist members supported by the rebels to his cabinet. Two additional positions have also been promised.

Some 40,000 people have been killed and tens of thousands displaced since the insurgency began in 1969.

The communists' armed wing, the New People's Army (NPA), has about 4,000 guerillas today, according to the military. That number is down from a peak of about 26,000 in the 1980s. The NDF maintains significant support and the ability to mobilize.

The talks in Norway were led by NDF exiles based in the Netherlands. According to Stanford University's Mapping Militant Organizations project, peace talks in the past were hampered by divisions between the Netherlands-based exile group and the communist party-NPA leadership on the ground.

The restart of negotiations comes as the Philippines faces multiple long-running insurgencies, including the brutal Abu Sayyaf Islamist movement tied to al-Qaeda. The threat posed by growing Islamist insurgencies has forced the government to focus its military strength on battling these groups.

The Philippine's many insurgencies have stunted economic growth, handed the military greater powers and unleashed a cycle of human rights abuses.

cw/rs (AP, AFP, Reuters)