Progressive groups blamed Philippine President Rodrigo Duterte for the latest series of killings and arrests in different parts of the country, Rappler reported on Monday.

Human rights organization Karapatan confirmed that at least five were killed and three were arrested in simultaneous raids by combined forces of the military and police in Laguna, Rizal, Cavite and Batangas on Sunday.

The deadly clampdown came just two days after Duterte ordered the Philippine National Police and the Armed Forces of the Philippines to "kill" and "finish off" communist rebels in encounters.

Members of the House minority bloc said the killings and arrests were carried out almost in an instant that the president gave the signal.

According to former progressive group Anakpawis Rep. Ariel Casilao, those who died, however, are not combatants of the New People's Army (NPA) but leaders and members of socio-civic organizations.

"Based on these reports, these raids appear to be part of a coordinated plan by the authorities to raid, arrest, and even kill activists in their homes and offices," Rappler quoted Human Rights Watch deputy Asia chief Phil Robertson as saying.

House Deputy Minority Leader and Bayan Muna Rep. Carlos Isagani Zarate, together with fellow Bayan Muna representatives Eufemia Cullamat and Ferdinand Gaite, denounced the killings.

Karapatan and the Kabataan Youth Party contested the government's claim, saying the slain individuals were "executed".

Karapatan Secretary General Cristina Palabay called on the Philippines Commission on Human Rights to investigate the "Bloody Sunday" crackdown by government forces.

"Our calls for justice ring louder more than ever as we demand the release of all those arrested in Southern Tagalog and all political prisoners, and to hold accountable the perpetrators of the killings in the region today," Palabay said in remarks quoted by Bulatlat News.

The Public Interest Law Center (PILC) also condemned the incidents, saying the spate of killings and continuous red-tagging clearly shows the "real targets of Duterte's kill order."