North Korea’s leader Kim Jong-un and US President Donald Trump will meet before May to discuss an end to nuclear and missile testing, after a South Korean delegation brokered an agreement between the pair.

Mr Trump confirmed via social media that the unprecedented meeting was “being planned”, after South Korean officials announced they had handed the President a letter containing an invitation from the North Korean leader.

The announcement follows a visit to North Korea by a 10-member South Korean delegation with a mission to encourage a dialogue between North Korea and the US.

Mr Trump said Kim Jong-un discussed denuclearisation with the South Korean representatives, “not just a freeze”.

Kim Jong Un talked about denuclearization with the South Korean Representatives, not just a freeze. Also, no missile testing by North Korea during this period of time. Great progress being made but sanctions will remain until an agreement is reached. Meeting being planned!

— Donald J. Trump (@realDonaldTrump) March 9, 2018

South Korea’s National Security Office head Chung Eui-yong told reporters at the White House on Thursday Kim Jong-un had pledged North Korea will refrain from any further nuclear or missile tests.

“President Donald Trump appreciated this briefing and said that he would meet Kim Jong-un by May,” Mr Chung said.

North Korea ramped up its nuclear program in 2017, testing 23 ballistic missiles. In November, the regime tested a new type of intercontinental ballistic missile capable of targetting the US mainland. 

Mr Chung and National Intelligence Service chief Suh Hoon flew to Washington to explain North Korea’s stance on possible future talks with Washington and the prospect of Pyeongyang suspending nuclear tests if the security of the North’s government is assured.

“We explained and he [Donald Trump] understands the routine military exersies in the Republic of Korea and the United States must continue,” he said.

“I expressed the favouritism of [South Korean Prime Minister] Lee Nak-yeon to him and he expressed his eagerness to meet Donald Trump as soon as possible.”

White House spokeswoman Sarah Huckabee Sanders said Mr Trump greatly appreciated the nice words of the South Korean delegation and President Moon Jae-in.

“He will accept the invitation to meet with Kim Jong-un at a place and time to be determined.

“We look forward to the denuclearisation of North Korea. In the meantime all sanctions and maximum pressure must remain.”

Earlier on Thursday (US time), US Secretary of State Rex Tillerson said while “talks about talks” might be possible with Pyeongyang, denuclearisation negotiations were likely a long way off.

But a senior US official said there was a growing recognition at the White House that the North Korean letter, with the support of South Korea, has pressured the United States to form a dialogue.

The International Campaign to Abolish Nuclear Weapons commended the South Korean leadership in achieving a historical dialogue between the United States and North Korea.

“We urge both North Korea and the United States to join the majority of countries in pursuing permanent denuclearization through The Treaty on the Prohibition of Nuclear Weapons,” ICAN executive director Beatrice Fihn said.

The South Korean delegation, the first to meet Kim Jong-un since he took control of North Korea in 2011, held high-level meetings on Monday and Tuesday, and dined with the North Korean leader on Monday night.

Mr Chung told media on his return to Seoul on Tuesday night that Pyeongyang expressed willingness to talk to the United States “in an open-ended dialogue to discuss the issue of denuclearisation and to normalise relations with North Korea”.

Pyeongyang said it would have no reason to retain nuclear weapons if “the military threat to North Korea is resolved” and the country’s security can be guaranteed, Mr Chung said.

Mr Trump responded on Wednesday tweeting he saw “possible progress” from the South Korean meeting.

“Possible progress being made in talks with North Korea. For the first time in many years, a serious effort is being made by all parties concerned. The World is watching and waiting! May be false hope, but the US is ready to go hard in either direction!” Mr Trump wrote.

North and South Korea are still technically at war but have enjoyed a sharp easing in tension since the Winter Olympics in Pyeongchang last month.

North and South Korea will also hold their first summit in more than a decade next month at the border village of Panmunjom, Mr Chung said.

– with AAP