The White House has said that it was moving forward with plans for a summit meeting between President Donald Trump and North Korean leader Kim Jong Un, despite North Korea's threat to pull out of it.

North Korea threatened to pull out of the 12 June summit in Singapore, if the US insists it give up its nuclear programme.

"Nothing has changed on our end," White House spokeswoman Sarah Sanders told reporters. 

"This was an invitation that North Korea offered, and that we've accepted, and we're continuing to move forward in those preparations."

"The president is prepared and will be ready to meet, and we're continuing to move forward with the preparations at this point," she said.

After weeks of warm words and diplomatic backslapping, North Korea on Tuesday abruptly threatened to pull out of the summit, blaming US demands for "unilateral nuclear abandonment".

In an angrily worded statement, the North warned "if the US is trying to drive us into a corner to force our unilateral nuclear abandonment, we will no longer be interested in such dialogue".

Ms Sanders, however, said North Korea was "not in the driver's seat. Nothing could be further from the truth".

"They're the ones that extended the invitation. If they're happy to meet, we're happy to do that," she added.