Philippine leader Rodrigo Duterte on Tuesday told U.S. President Barack Obama to "go to hell" and said the United States had refused to sell some weapons to his country but he did not care because Russia and China were willing suppliers.

In his latest salvo, Duterte said he had lost respect for the United States and railed at its concerns about his bloody war on drugs, calling his critics "fools" who could not stop him carrying out a campaign that has killed more than 3,400 people in just over three months.

In a tangential, at times profane speech in Manila, Duterte said the United States did not want to sell missiles and other weapons, but Russia and China had told him they could provide them easily.

"Although it may sound shit to you, it is my sacred duty to keep the integrity of this republic and the people healthy," Duterte said in his second of two televised speeches on Tuesday.

"If you don't want to sell arms, I'll go to Russia. I sent the generals to Russia and Russia said 'do not worry we have everything you need, we'll give it to you'.

"And as for China, they said 'just come over and sign and everything will be delivered'."

His comments were the latest in a near-daily avalanche of hostility towards the United States, during which Duterte has started to contrast the former colonial power with its geopolitical rivals Russia and China.

On Sunday, he said he had got support from Russia and China when he complained to them about the United States. He also said he would review a U.S.-Philippines Enhanced Defence Cooperation Agreement.

The deal, signed in 2014, grants U.S. troops some access to Philippine bases, and allows them to set up storage facilities for maritime security and humanitarian and disaster response operations.

He said the United States should have supported the Philippines in tackling its chronic drugs problems but instead criticised him for the high death toll, as did the European Union.

"Instead of helping us, the first to hit was the State Department. So you can go to hell, Mr Obama, you can go to hell," he said.

"EU, better choose purgatory. Hell is full already. Why should I be afraid of you?"

According to some U.S. officials, Washington has been doing its best to ignore Duterte's rhetoric and not provide him with a pretext for more outbursts.

While an open break with Manila would create problems in a region where China's influence has grown, there were no serious discussions about taking punitive steps such as cutting aid to the Philippines, two U.S. officials said on Monday.

Several of Duterte's allies on Monday suggested he act more like a statesman because his comments had created a stir. On Tuesday, he said his outbursts were because he was provoked by criticism of his crackdown on drugs.

"When you are already at the receiving end of an uncontrollable rush, the only way out is to insult," he said.

"That is my retaliation."