Republican presidential candidate Donald Trump has said that he is willing to talk to North Korean leader Kim Jong Un to try to stop Pyongyang's nuclear programme, proposing a major shift in US policy toward the isolated nation.

In a wide-ranging interview with Reuters, Trump also called for a renegotiation of the Paris climate accord, said he disapproved of Russian President Vladimir Putin's actions in eastern Ukraine, and said he would seek to dismantle most of the US Dodd-Frank financial regulations if he is elected president.

The presumptive Republican nominee declined to share details of his plans to deal with North Korea, but said he was open to talking to its leader.

"I would speak to him, I would have no problem speaking to him," he said.

Asked whether he would try to talk some sense into the North Korean leader, Trump replied, "Absolutely."

North Korea's mission to the UN did not immediately respond to a request for comment on Trump's remarks.

Trump, 69, also said he would press China, Pyongyang's only major diplomatic and economic supporter, to help find a solution.

"I would put a lot of pressure on China because economically we have tremendous power over China," he said in the interview in his office on the 26th floor of Trump Tower in Manhattan. "China can solve that problem with one meeting or one phone call."

Trump's preparedness to talk directly with Kim contrasts with President Barack Obama's policy of relying on senior US officials to talk to senior North Korean officials.

A South Korean foreign ministry official declined to respond directly to Trump's comments but said South Korea and the US were committed to denuclearization as the top priority of any dialogue with North Korea.

"North Korea must cease threats and provocations and show with action its sincere commitment to denuclearization," the official said by telephone.

Obama has not engaged personally with Kim, but he has pushed for new diplomatic overtures to Iran and Cuba that produced a nuclear deal with Tehran and improved ties with Havana.

Sitting at his desk with an expansive view of Central Park, Trump spoke at length about his economic and foreign policy ideas in the half-hour interview. Facing him on his desk is a framed photograph of his father, the late Fred Trump. A wall displays framed photos of Trump with various celebrities, as well as numerous magazine covers on which he has appeared.

On Russia, Trump tempered past praise of Putin, saying the nice comments the Russian leader has made about him in the past would only go so far.

"The fact that he said good things about me doesn't mean that it's going to help him in a negotiation. It won't help him at all," he said.

An adviser to Hillary Clinton, the leading Democratic presidential candidate, criticised Trump's foreign policy comments, noting they came soon after Trump said he was unlikely to have a good relationship with British Prime Minister David Cameron.

"Let me get this straight: Donald Trump insults the leader of our closest ally, then turns around and says he'd love to talk to Kim Jong Un?" Clinton's senior foreign policy adviser, Jake Sullivan, said in a statement.

Trump "seems to have a bizarre fascination with foreign strongmen like Putin and Kim. But his approach to foreign policy makes no sense for the rest of us," he said.

In the Reuters interview, Trump said he thought Cameron's criticism of him was inappropriate but "I'm sure I'll have a good relationship with him."

CLIMATE ACCORD

Trump 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 US unfairly and gives favourable treatment to countries like China.

"I will be looking at that very, very seriously, and at a minimum I will be renegotiating those agreements, at a minimum. And at a maximum I may do something else," he said.

A renegotiation of the pact would be a major setback for what was hailed as the first truly global climate accord, committing both rich and poor nations to reining in the rise in greenhouse gas emissions blamed for warming the planet.

Trump has been criticised for offering far fewer specific policy proposals than Clinton, his likely rival for the Nov. 8 presidential election.

The New York billionaire said he planned to release a detailed policy platform in two weeks that would propose dismantling nearly all of Dodd-Frank, a package of financial reforms put in place after the 2007-2009 financial crisis.

"Dodd-Frank is a very negative force, which has developed a very bad name," he said.

Trump took a dim view of Clinton's stated desire to put her husband, former President Bill Clinton, in charge of building up the US economy.

"The wife wants to make him in charge of the economy," he said.

Clinton described Trump's idea of dismantling Dodd-Frank as reckless. "Latest reckless idea from Trump: gut rules on Wall Street, and leave middle-class families out to dry," she said on Twitter.

FINANCIAL BUBBLE?

Trump said he perceived a dangerous financial bubble in the tech start-up industry, with some companies selling shares at high valuations without ever turning a profit.

"I'm talking about companies that have never made any money, that have a bad concept and that are valued at billions of dollars," he said.

Silicon Valley investors responded on Twitter by poking fun at Trump's campaign slogan "Make America Great Again!" by repeating the phrase, "Make Bubbles Great Again."

On the US Federal Reserve, Trump said that while he eventually wants a Republican to head it, he is "not an enemy" of current chair Janet Yellen, who was appointed by Obama.

"I'm not a person that thinks Janet Yellen is doing a bad job. I happen to be a low-interest rate person unless inflation rears its ugly head, which can happen at some point," he said, adding that inflation "doesn't seem like it's happening any time soon."

The real estate mogul said he would maintain the current level of benefits for Social Security recipients, a position championed by former Republican presidential candidate Mike Huckabee. Trump said he would not raise the retirement age or impose a sliding scale of benefits depending on income levels.

Some Republican lawmakers have pushed for structural reforms to Social Security to extend its solvency.

The depleted Social Security Trust Fund, Trump said, would be replenished by the increased tax revenue that would flow into the government from the higher job growth spurred by his economic policies. - Reuters