The Philippine government and communist rebels have opened peace talks in Norway, seeking to end nearly five decades of conflict that has killed tens of thousands of fighters and civilians.

Negotiators declared on Monday that they hoped to reach a deal within nine months to a year, and expressed optimism that the talks, the first formal meeting in five years, would be successful under the administration of President Rodrigo Duterte.

There is fresh euphoria among our people about the prospects of peace negotiations.

Jesus Dureza, government negotiator

"There is fresh euphoria among our people about the prospects of peace negotiations," Jesus Dureza, a top government negotiator, said at the opening of the talks in Norway's capital, Oslo.

Both sides announced ceasefires starting on Sunday before the five-day negotiations

Duterte has stressed the need to end the conflict, and the rebels praised him on Monday for steps such as the release of 17 prisoners to attend the Oslo meeting, and the appointment of what they called progressives to cabinet posts, including politicians backing agrarian reform.

"Duterte has shown magnanimity and generosity," Jose Maria Sison, the exiled founder of the Communist Party of the Philippines who lives in the Netherlands, said.

The two delegations shook hands, gave "V" for victory signs with their fingers and smiled at the start of the talks between.

Six negotiators from each side faced each other in the Holmenkollen Park Hotel's "Nobel" room, named after the Nobel Peace Prize.

'Timeline to peace'

"We have imposed a timeline of nine to 12 months," Silvestre Bello, the labour minister and head of the government team, said.

Bello's counterpart on the rebels' side, Luis Jalandoni, told the Reuters news agency that a year was "optimistic" given the huge differences, including issues covering land and labour reform. 

President Duterte declares ceasefire with communists

Still, he said it was likely that the communists would extend the ceasefire if the Oslo talks went well.

Boerge Brende, Norway's foreign minister, told the meeting that there seemed to be a "historic momentum" building to end the conflict.

"I'm really crossing my fingers," he said.

The talks faced an early hurdle in July, when Duterte abruptly ended a unilateral ceasefire, after the rebels did not respond to a deadline to reciprocate his move, and following the death of a government militia member. 

The peace negotiations had been suspended in 2012 after former president Benigno Aquino rejected rebel demands to free political prisoners.

The rebels have been waging an armed rebellion to seize power since 1969.

The military estimates the current strength of the rebel fighters at about 4,000, significantly down from more than 26,000 at its peak in the late 1980s.

Jose Maria Sison, founder of the Communist Party of the Philippines, left, with government representative Jesus Dureza in Oslo on Monday [EPA]

Source: Agencies