Kim Jong Un tells Chinese President Xi Jinping that he also wants to further improve relations between the two countries.

North Korean leader Kim Jong Un has sent a message to Chinese President Xi Jinping congratulating him on the Beijing Winter Olympic Games as a “great victory” and saying he wants to improve relations between their countries, according to state news agency KCNA.

“The successful opening of the Beijing Winter Olympics despite the worldwide health crisis and unprecedented severe circumstances is another great victory won by socialist China,” Kim said in the letter, KCNA reported on Friday.

Kim said that he would “steadily develop the relations between the two parties and the two countries to a new high stage”.

He said the ties between the two countries “have been cemented into invincible strategic relations that can never be broken by anything in the struggle for defending and advancing the common cause”.

The Winter Olympics are due to open in Beijing later on Friday.

The United Nations Security Council will meet the same day to discuss a record month of North Korean missile tests, including the launch of an intermediate-range ballistic missile on Sunday, the first test of that type since 2017.

China and Russia last month delayed a US bid to impose UN sanctions on five North Koreans, diplomats said.

In a previous letter from sports authorities in January, North Korea said it would not be attending the Games in neighbouring China, blaming COVID-19 risks and “hostile forces” from other countries, although it did not mention specific nations.

North Korean athletes are not eligible to compete under their national flag after the country was suspended from the International Olympic Committee (IOC) until the end of 2022 for failing to send a team to the Tokyo Summer Olympics last year, citing COVID-19 concerns.

The earlier letter also criticised unspecified moves by the United States, which in December announced that its government officials would boycott the 2022 Winter Olympics because of China’s human rights record while leaving US athletes free to travel to Beijing to compete.

China has been North Korea’s only major ally since the two signed a treaty in 1961, and international sanctions imposed over Pyongyang’s nuclear weapons and ballistic missile programmes have made it more dependent than ever on Beijing for trade and other support.

After nearly two years of some of the world’s strictest border closures in the pandemic, North Korea resumed limited trade by train with China last month, but maintains near-total lockdowns on other border travel.