Troops in the Philippines have killed four communist rebels during clashes in the eastern part of the country, a regional police spokesperson said.

The slain fighters included a regional commander of the New People's Army, the armed wing of the rebel group known as the Communist Party of the Philippines, police superintendent Nonito Marquez said on Friday.

No casualties were reported on the military side, Marquez said.

The soldiers were on patrol when they encountered about 30 rebels in a village in the province of Sorsogon, 383 kilometres south-east of Manila, he said.

The firefight marked the latest clash between communist rebels and government forces since President Rodrigo Duterte scrapped peace talks after a series of attacks by the rebels.

Government troops are also fighting in the southern Philippines against hundreds of fighters allied with the Islamic State of Iraq and the Levant group (ISIL, also known as ISIS) who have laid siege to Marawi City since May 23.

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"No more talks," he declared on Monday at a press conference after his state of the nation address in congress, vowing to prepare the armed forces for war by recruiting at least 20,000 more soldiers and purchasing new equipment.

Communists next target after ISIL 'fools'

Last week, soldiers and communist rebels engaged in tit-for-tat attacks that left several dead, prompting Duterte to threaten to launch a new offensive against communist fighters.

"After we finish off those [ISIL] fools there, we will re-orient our offensive against the New People's Army," he said, referring to the armed wing of the rebel group the Communist Party of the Philippines.

Documents recently obtained by the army allegedly showed Maoist rebel leaders had ordered fighters to step up attacks after martial law was imposed in Mindanao on May 23, Ano said.

Peace talks between the government and Netherlands-based communist rebel leaders have been suspended since May.

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In April, government and communist rebel negotiators agreed to an interim ceasefire, but they have not yet finalised the guidelines and rules that would make the truce effective.

Communist rebels have been fighting the Philippine government since the late 1960s, making the movement one of the longest-running leftist armed uprisings in Asia.

Communists reportedly shot dead two soldiers who were buying supplies at a public market in the town of Roxas in Palawan province, 510 kilometres south-west of Manila, on July 19.

That same day, Maoist fighters attacked a checkpoint on the Mindanao Island, killing a paramilitary guard officer and injuring five soldiers from the presidential guard.