MANILA (REUTERS) - Philippines President Rodrigo Duterte is taking seriously the US Intelligence Community's report tagging the firebrand leader a threat to democracy in South-east Asia, his spokesman said on Wednesday (Feb 21).

The report, produced by the Office of the Director of National Intelligence, places Duterte alongside Cambodian's Hun Sen, the Rohingya crisis and Thailand's military-backed constitution as threats to democracy.

"We view this declaration from no less than the intelligence department of the United States with some concern...," presidential spokesman Harry Roque told DZMM radio.

Roque rejected the US Intelligence assessment of Duterte as a threat to democracy.

"I do not think that's true. He is a lawyer, he knows the law, he wants to uphold the rule of law, he knows about the bill of rights," he said.

Democracy and human rights in many South-east Asian nations will remain fragile in 2018 because of autocratic tendencies, rampant corruption and cronyism, the US Intelligence Community said in its Worldwide Threat Assessment report dated Feb 13.

"In the Philippines, President Duterte will continue to wage his signature campaign against drugs, corruption, and crime," the report read, adding that Duterte has suggested he could suspend the constitution and declare a revolutionary government.

This is not the first time the United States has criticised Duterte, who is notorious for his defiance of international pressure.

Duterte was infuriated by expressions of concern by former President Barack Obama's administration about drug-war killings in the Philippines.

More than 4,000 people have been killed in what police call legitimate operations against suspected drug dealers and users under the Duterte's signature war on drugs since July 2016.

Rights group accused police of summary executions, which the authorities refute.

International Criminal Court prosecutors have opened a preliminary examination into Duterte's anti-drugs campaign.