North Korea has accused United Nations Secretary-General Antonio Guterres of siding with South Korea, after he urged the two Koreas to ease tensions through dialogue following a landmine blast at their shared border.

Kim Yo Jong, the influential sister of North Korean leader Kim Jong Un, said Mr Guterres had taken a "prejudiced and irresponsible" attitude by echoing South Korea's account of the September explosion, according to a statement carried by the state-run KCNA news agency on Tuesday.

The UN chief had called last week for the two sides to restore communication channels, including at the military level, to avoid unintended accidents or miscalculations on the Korean Peninsula.

Kim Yo Jong rejects dialogue call

"I express my regret over the fact that the top official of the UN, which regards impartiality and objectivity as its lifeline, took such a prejudiced and irresponsible attitude as echoing the ROK's unilateral and provocative sophism," Kim said, using South Korea's official name, the Republic of Korea.

She said the UN secretary-general's behaviour in "echoing words of the provokers and patronising them without having proper understanding of the fact is not helpful to the detente".

Kim also warned that if what she called the "reckless military provocations of the ROK gangsters" led to an undesirable incident in the southern border area, Mr Guterres "will never be free from the blame for it".

The DMZ mine blast behind the row

Tensions between the two Koreas, which remain technically at war, have risen sharply since a landmine exploded inside the Demilitarised Zone (DMZ) on 21 September, seriously wounding three South Korean soldiers on a reconnaissance mission.

Seoul has said the blast was caused by North Korean mines. A joint investigation by South Korea's military and the UN Command concluded that the explosion was caused by antipersonnel mines deliberately planted by North Korea south of the Military Demarcation Line.

Pyongyang has denied responsibility, saying its troops were carrying out fortification work along the border and had not violated the UN Charter or international law. It has also told the UN Security Council that Seoul fabricated the incident.

South Korea raised the incident with the Security Council in a letter dated 22 October, calling on Pyongyang to apologise, remove the mines and take steps to prevent a recurrence.

Border fortification work continues

In Tuesday's statement, Kim Yo Jong defended North Korea's efforts to fortify its southern border, describing them as the most righteous and reasonable exercise of its right to self-defence.

UN spokesperson Stephane Dujarric told reporters that Mr Guterres had encouraged the two Koreas to resume dialogue, including on the military level, to avoid unintended accidents.

North Korea has enshrined its status as a nuclear-armed state in law and has repeatedly ruled out giving up its nuclear weapons, despite long-running UN sanctions and repeated calls from Washington, Seoul and Tokyo for complete denuclearisation.