MANILA (REUTERS) - The Philippines has freed 12 communist guerrilla leaders, police said on Thursday (Aug 18), days before a new round of peace talks with the Maoist-led rebels resumes in Norway to end nearly five decades of conflict that has killed more than 40,000 people.

New President Rodrigo Duterte has a reputation as an implacable and ruthless enemy of drug traffickers but he came to power after winning a May election promising to negotiate the end of long-running insurgencies.

Talks brokered by Norway between the government and the rebels' National Democratic Front stalled in 2012 over the refusal of the government to free communist leaders who had been in jail for decades.

National police chief Ronald dela Rosa told reporters the temporary release of the 12 by courts was a consequence of the president's peace offer and was "one of the most positive developments" in years.

"They were only allowed to post bail," he said. "But they continue to face criminal cases in courts."

Mr Renato Reyes, secretary-general of the left-wing Bayan (Nation) group, which is allied with the communist movement, said the releases boded well and raised hopes the talks would begin on Aug 22 "on a positive note".

Among those freed were Adelberto Silva, Concha Araneta Bocala, Alan Jazmines and Tirso Alcantara. Alcantara, one of the country's highest ranking guerrilla leaders, was wounded in a firefight with soldiers five years ago.

The rebels' top leaders, Benito Tiamzon and his wife, Wilma, are still in prison. Activists are holding a protest outside the national police office on Friday to demand the release of them and six others senior guerrilla commanders.

Leftist lawmakers and human right advocates said the government is holding more 500 rebels in detention.