US President Donald Trump has said he's in love with Kim Jong Un, but Secretary of State Mike Pompeo on Tuesday agreed that the North Korean leader is a "tyrant."

Pompeo, who flew to Pyongyang four times last year as the Trump administration sought an opening with North Korea, was taken to task as he testified before a Senate subcommittee.

"Sure. I'm sure I've said that," Pompeo replied.

The comment may irk North Korea, which has signalled it is open to a third summit with Trump after a February meeting in Hanoi ended in stalemate.

Seeking a potentially landmark denuclearisation accord, Trump has repeatedly praised Kim and last month said he had blocked major new sanctions planned for North Korea out of affection for its young authoritarian leader.

North Korea has also been careful not to criticize Trump, while accusing his aides of "gangster-like" behaviour.

Pompeo, however, was unwilling to label as a tyrant Egypt's military ruler turned president, Abdel Fattah al-Sisi, who was hailed by Trump earlier Tuesday in a White House meeting.

"There's no doubt that it's a mean, nasty world out there. But not every one of these leaders is the same," Pompeo said.

"Some of them are trying to wipe entire nations off the face of the Earth and other are actually partnering with us to help keep Americans safe," he said.

"You might call them tyrant, you might call them authoritarian, but there a fundamental difference, and therefore a fundamental difference in the way the US should respond," he said.

Pompeo hailed Sisi's offensive against fighters of the Islamic State extremist movement in the Sinai peninsula.

Sisi took power in a 2013 coup against elected president Mohamed Morsi, an Islamist, with authorities shortly afterward killing 700 protesters who had assembled in two Cairo squares.

Human rights group say that North Korea has one of the world's most egregious records, with Kim's regime forbidding all dissent and running a massive system of political prisons in which between 80,000 and 130,000 people are detained along with their family members for suspected dissent.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)