North Korea could consider a change of approach if the US maintains its sanctions on the nuclear-armed country, leader Kim Jong-un has warned in his New Year speech, after 12 months of diplomatic rapprochement.

“If the US does not keep its promise made in front of the whole world… and insists on sanctions and pressures on our republic,” Mr Kim said, “we may be left with no choice but to consider a new way to safeguard our sovereignty and interests”.

Mr Kim was referring to his summit with US President Donald Trump in Singapore in June, when he said he had “fruitful talks” and “exchanged constructive ideas”.

At the time the two leaders signed a vaguely worded pledge on denuclearisation of the Korean peninsula, but progress has since stalled with the sides arguing over what that means.

The North is subject to multiple sets of United Nations Security Council sanctions over banned nuclear and ballistic missile weapons programmes, which have seen it carry out six atomic tests and launch rockets capable of reaching the US mainland.

“I am ready to sit with the US president again at any time in the future and will make efforts by all means to produce a result that will be welcomed by the international community,” Mr Kim said in his address, broadcast by the North’s state television.