Incoming Philippine president Rodrigo Duterte will resume stalled peace talks with communist rebels next month, negotiators said, a step towards ending one of Asia's longest insurgencies that has killed tens of thousands of people.

The long-running talks collapsed in 2013, but Duterte had made a campaign pledge to revive the negotiations aimed at bringing a swift political settlement to a decades-old rebellion.

"Formal peace talks will resume in the third week of July 2016 in Oslo, Norway," the two sides said in a joint statement late Wednesday after a two-day meeting in the Scandinavian capital.

Duterte, who assumes office on June 30, has offered to declare a ceasefire and promised to free ailing or ageing communist rebels. He has also named two rebel allies to his cabinet.

At the informal meeting in Norway, whose government has acted as a go-between in the talks, the two sides agreed to discuss amnesty for all political prisoners, subject to the approval of the Philippine legislature. They will also talk about setting up an interim ceasefire and a timeline for talks, according to the statement.

Duterte's negotiators also said they would recommend some detained communist rebels be allowed to participate in the talks, a move the rebel side has been pushing for.

Outgoing President Benigno Aquino revived negotiations soon after taking office in 2010 but shelved them in 2013, accusing the rebels of being insincere about finding a political settlement.

The talks collapsed after his government rejected the rebels' demand to release scores of their jailed comrades, whom they described as "political prisoners".

The communist rebellion has killed about 30,000 people since the 1960s and impoverished vast swathes of the country.

The communists' armed wing, the New People's Army, is believed to have fewer than 4,000 gunmen today, down from a peak of 26,000 in the 1980s, according to the military, but it retains support among the deeply poor in rural areas.