Philippine President Rodrigo Duterte has described North Korean leader Kim Jong-un as a "maniac" who could destroy Asia by touching off a nuclear war.

The remark came before a regional summit on Wednesday in the capital, Manila, to be attended by the North Korean foreign minister.

Using characteristically crude language, Duterte attacked Kim in advance of the regional security meeting where the ballistic-missile tests will be a key item on the agenda.

"He is playing with dangerous toys and this crazy man, do not be fooled by his face, that chubby face that looks nice," Duterte, 72, said of Kim in a nationally televised speech.

"That son-of-a-wh*re maniac, if he makes a mistake then the Far East will become an arid land. It must be stopped, this nuclear war, because [if] a limited confrontation blows up here, I tell you the fallout, the soil, the resources.

"I don't know what will happen to us. We won't be able to plant anything productive."

Under Kim's leadership, North Korea has accelerated its nuclear ambitions in defiance of international condemnation and multiple sets of UN sanctions.

North Korea last week conducted its second intercontinental ballistic missile (ICBM) test, which led Kim to boast that he could strike any target in the US.

Rex Tillerson, the US secretary of state, and Wang Yi, China's foreign minister, will also be in Manila for the security forum, which is hosted by the 10-member Association of Southeast Asian Nations (ASEAN).

The ministers will express "grave concern" over North Korea's nuclear missile test, according to a draft copy of the chairman's statement obtained by AFP news agency and scheduled to be released on Tuesday next week at the end of the ASEAN Regional Forum.

Crude language

Duterte, who won presidential elections last year, has come under fire from foreign leaders over his war on drugs that has claimed thousands of lives.

He typically flavours his speeches with crude language and jokes deemed by many to be offensive, including about rape.

Duterte last year called then US President Barack Obama a "son of a whore" for criticising the drug war.

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Source: AFP news agency