Had to fight this way: Trump

Presumptive US Republican presidential candidate Donald Trump has admitted he "has regrets" about his US election campaign but said he would not have been successful otherwise.

He was speaking to Fox News presenter Megyn Kelly, with whom he has had a feud since a TV debate last August.

The interview with Kelly was largely seen as an attempt to bury the hatchet after months of rancour between the two, with the journalist taking the initiative to set it up.

In another interview, he said he was open to meeting North Korea's leader.

During the August debate, Kelly had probed Trump on his comments about women. Afterwards, he insinuated she had treated him unfairly because she was menstruating.

"You could see there was blood coming out of her eyes, blood coming out of her - wherever," he said.

When pressed about why he re-tweeted "bimbo" jibes about her, he said: "Did I say that? Ooh. Excuse me."

He added: "When I'm wounded. I go after people hard and I try and un-wound myself."

Kelly also asked if Trump had any regrets about his nine-month campaign. He said: "Absolutely, I have regrets... I could have done certain things differently." He would not specify what the regrets were.

He added: "If I didn't conduct myself in the way I've done, I don't think I would have been successful."

In an interview with Reuters news agency late on Tuesday, Trump said he would be willing to meet North Korea's leader to discuss its nuclear programme.

Such a meeting would mark a significant change of US policy towards the politically isolated regime. Democratic front-runner Hillary Clinton decried Trump's "bizarre fascination with foreign strongmen".

Trump also said he is "not a big fan" of the Paris climate accord, which prescribes reductions in carbon emissions by more than 170 countries. He said he would want to renegotiate the deal because it treats the United States unfairly and gives favorable treatment to countries like China.

Trump also claimed again that he is worth "in excess of $10 billion" -- more than twice the level of independent estimates.