The United States and North Korea will hold further talks next week to prepare for a second summit between President Donald Trump and Kim Jong Un later this month, Seoul said Sunday.

The news comes a day after Stephen Biegun, the US Special Representative for North Korea, said more dialogue was needed ahead of the summit scheduled in Vietnam.

"North Korea and the US have agreed to continue negotiations in a third country in Asia during the week of February 17," Seoul's presidential spokesman Kim Eui-kyeom told reporters.

He did not provide further details.

Biegun travelled to Pyongyang earlier this month for three days of preparatory meetings with North Korean officials, with the State Department saying the talks focused on Trump and Kim's "commitments of complete denuclearisation, transforming US-DPRK relations and building a lasting peace on the Korean Peninsula".

Trump and Kim are due to meet in Hanoi from February 27 to 28 following their landmark first summit in Singapore last June.

That meeting -- the first-ever between the leaders of the US and North Korea -- produced a vaguely-worded document in which Kim pledged to work towards "the denuclearisation of the Korean peninsula".

But progress has since stalled with the two sides disagreeing over what that means and analysts say tangible progress on denuclearisation will be needed for the second summit if it is to avoid being dismissed as "reality TV".

Trump's own intelligence chief, Dan Coats, have expressed scepticism over the North's denuclearisation, and told the Senate Intelligence Committee that Pyongyang was "unlikely to completely give up its nuclear weapons".