SEOUL/BEIJING: A senior North Korean diplomat left for Finland on Sunday for talks with former US and South Korean officials, Yonhap News Agency reported, amid a series of diplomatic encounters ahead of a possible US-North Korean summit.

North Korea is pursuing its nuclear and missile programmes in defiance of UN Security Council sanctions and has made no secret of its plans to develop a missile capable of hitting the US mainland.

It defends the programmes as a necessary deterrent against perceived plans by the United States, which stations 28,500 troops in South Korea, a legacy of the Korean war, for invasion.

The United States denies such plans. Tensions have eased in recent weeks, coinciding with North Korea's participation in the Winter Olympics held in the South last month.

Choe Kang Il, a deputy director general for North American affairs at North Korea's foreign ministry, plans to attend the "track 1.5 talks", according to Yonhap, reflecting planned contact between former US officials and current North Korean ones in a broader bid to end the standoff over North Korea's weapons programmes.

South Korea's foreign ministry said in a statement North Korea would participate in the meeting joined by former South Korean officials and academics but did not provide further details.

The talks in Finland will add to a flurry of diplomatic activity in face of the proposed North Korean summits with South Korea and the United States, respectively, in April and May.

Arriving at a Beijing airport en route to Finland, Choe declined to comment.

North Korean and Swedish foreign ministers ended three days of talks on Saturday on security on the Korean peninsula in preparation of the meeting between US President Donald Trump and Kim Jong Un.

South Korea said on Friday it was seeking high-level talks this month with North Korea to prepare for a summit and that South Korean President Moon Jae-in may meet Trump before the US president's planned meeting with the North Korean leader.

In a telephone call, Moon and Trump both voiced "cautious optimism" about efforts to resolve the crisis over North Korea's nuclear weapons.