North Korea has accused the United States of being "hell-bent" on hostile acts, just days after the two countries' leaders met at the demilitarized zone on the Korean peninsula and agreed to resume nuclear talks.

The North Korean complaint came after the US sent a letter to all UN member-states urging them to send back North Korean workers.

North Korea's UN mission said the letter was sent on 29 June, the day US President Donald Trump tweeted that he would like to shake North Korean leader Kim Jong-un's hand and say hello during his visit to the demilitarised zone.

It added that this showed that the US is "practically more and more hell-bent on the hostile acts" against North Korea, even though it is seeking dialogue.

The letter, from the US, Britain, France and Germany, was in fact sent on 27 June and called on all countries to apply sanctions provisions that call for the return of all North Korean workers by the end of 2019.

In the letter, the four countries noted that only 34 countries had filed reports to the United Nations on whether action was taken to send North Korean workers back.

UN experts estimate that tens of thousands of North Koreans are sent abroad every year, mostly to China and Russia, working in slave-like conditions to generate hard currency revenue for Pyongyang.

The North Korean mission said it was "quite ridiculous" for the US to consider sanctions as a "panacea for all problems".

UN sanctions resolutions have banned all new contracts with North Korean workers and demands all countries with existing workers will send them back by the end of 2019. 

The UN Security Council has adopted a series of sanctions in response to the North's ballistic missile and nuclear tests.