The US president's discussion with Rodrigo Duterte is likely to reinforce the impression that Mr Trump is sidelining human rights concerns in his foreign policy.

He has met several authoritarian leaders since taking office in January, offering few criticisms of their records on democracy, the rule of law and protecting freedoms.

The transcript of the April 29 call was first posted by the Washington Post. It is marked confidential and is contained under a cover sheet from the Philippine Foreign Ministry.

Neither the Philippine government nor the White House verified the transcript, but they did not dispute its contents either.

It also shows the leaders discussing the North Korean threat, with each referring to the North's ruler, Kim Jong Un, as a "madman".

In an unusual disclosure of the movements of American military assets, Mr Trump revealed the US had two nuclear submarines in the region, although he said the States did not want to use them.

Democratic legislators criticised Mr Trump for his reported comments.

"Today's reporting leaves me even more concerned by President Trump's strange fascination with dictators, his support for the extra-judicial killings central to President Duterte's 'drug war', and his recklessness with sensitive information," said Eliot Engel, top-ranking Democrat on the House foreign affairs committee.

Twelve Democratic senators wrote to Mr Trump calling for him to denounce the "murderous" anti-drug campaign and delay any visit by Mr Duterte to Washington until there are improvements in his human rights record.

At the time of the call, Mr Trump raised hackles in Washington by inviting Mr Duterte to the White House.

Since Mr Duterte took power in June, his anti-drug campaign has killed between 7,000 and 9,000 suspected dealers and addicts, according to human rights groups.