MANILA (UPDATE) - President Rodrigo Duterte's order for the justice department to investigate the entire government for corruption covers lawmakers, his spokesman said Tuesday.

Sen. Panfilo Lacson earlier said lawmakers and officials of the Department of Public Works and Highways (DPWH) asking for "kickbacks" from contractors that won projects from the agency have become an "open secret".

DOJ's mandate, under the law that created the National Prosecutors Office, is "to investigate everyone", said Presidential Spokesperson Harry Roque.

"Mayroon din po tayong mga immunities na ini-enjoy ang ating mga elected members of Congress and the Senate, pero it is not for violating anti-graft laws," he told reporters.

(Our elected members of Congress and the Senate enjoy certain immunities, but it is not for violating anti-graft laws.)

"So, kasama po ang lahat po ng mga public offices [sa imbestigasyon] despite the separation of powers dahil wala naman pong separate na ahensiya na nag-iimbestiga ng korapsiyon sa Kongreso mismo. Iyan po ay kapangyarihan ng ehekutibo, to implement the laws to all kahit sino pa man sila," he added.

(So, all public offices are included in the investigation despite the separation of powers because there is no separate agency that investigates corruption in Congress itself. That is a power of the executive, to implements law to all, no matter who they are.)

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Lawmakers and members of other government branches will be investigated if they are involved in criminal or corrupt acts with the executive department, Justice Secretary Guevarra said.

"Natural dahil kung 'yun ay incidental to the investigation of an executive agency kung may part sa isang criminal act, di naman natin tinitingnan kung siya ay miyembro ng Kongreso, hudikatura o executive department," he said.

(If their involvement is incidental to the investigation of an executive agency, if they were part of a criminal act, we do not look at them as a member of Congress, judiciary or executive department.)

"Sama-sama 'yan because it’s a criminal act, the corrupt act na tinitingnan natin. Kung may ebidensiya ng kanilang involvement, direct o indirect, ay kasama sila."

(They're all included because we look at the criminal act, the corrupt act. If there's evidence of their involvement, direct o indirect, they are included."

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In 2016, Duterte won the presidency campaigning on a promise to fight corruption, crime, and illegal drugs.

But his administration has been dogged by scandals and allegations of graft and cover-ups in state agencies ranging from prisons, the state insurer, immigration, airports and customs, to police and the drugs enforcement agency, few of which led to convictions or high-profile resignations.

On Tuesday, Duterte issued a memorandum directing the justice ministry to look into anomalies at state agencies until the end of his term in 2022. It gives the ministry the power to decide what allegations to investigate and to work with other agencies.

"I hope that all government workers, officials are listening. This is a memorandum from me to Justice Secretary Menardo Guevarra... The subject is investigate of allegations of corruption in the entire government--Lahat (everything)," he said in a taped speech.

Guevarra is expected to invite the National Bureau of Investigation, Office of the Ombudsman, Civil Service Commission and state auditors to join the investigation, said Roque.

"Ito po ay isang (this is a) mega task force," Duterte's spokesman said.

The Philippines fell 14 notches to 113th spot among 180 countries in Transparency International's Corruption Perceptions Index last year.

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Duterte is not eligible for re-election, but fulfilling his campaign pledge on corruption could help the chances of his chosen successor in the 2022 elections.

The justice department said it would work with other government agencies on investigations.

"It will help us a lot if government workers themselves and the people they deal with would come forward and provide us the necessary information to uncover corrupt activities and identify the perpetrators," DOJ's Guevarra told reporters.

- With a report from Reuters