China caught between US-N Korea tug of war, even as the leaders congratulate Xi for win

Seoul/Washington: North Korean leader Kim Jong-Un wished his Chinese counterpart Xi Jinping "great success" in a congratulatory but comparatively restrained message after he cemented his grip on power at a landmark Communist Party Congress.

Kim's note extended "sincere congratulations" to the Chinese president, who was formally given a second term as the head of the ruling party, state-run KCNA said Thursday.

The message, sent Wednesday, also "expressed conviction that the relations between the two parties and the two countries would develop in the interests of the peoples of the two countries," KCNA said.

But the brief, four-sentence missive was a notable contrast to the fulsome terms in which Kim praised the Chinese leader and his country when Xi ascended to power five years ago.

Meanwhile, US President Donald Trump also congratulated Chinese President Xi Jinping for securing a second five-year term as the head of the ruling Communist Party, saying he looks forward to work together towards denuclearising North Korea.

Trump spoke to Xi over phone on the occasion of the closing of China's Party Congress. He welcomed continued cooperation of the two countries in the years ahead, the White House said.

"Trump told Xi he looks forward to visiting China in early November, and to advancing joint efforts to denuclearise North Korea," the White House said in a statement.

Xi, 64, has secured a second five-year term as the head of the ruling Communist Party as it unveiled its new leadership with the Chinese president attaining iconic status enjoyed by modern China's founder Chairman Mao Zedong.

He was elected in a closed-door vote to head the Politburo Standing Committee while premier Li Keqiang retained his seat on the ruling council alongside five new members.

Ties between the two neighbours have soured in recent years as the North staged a series of nuclear tests and missile launches despite opposition by Beijing - its sole diplomatic ally and economic lifeline.

North Korea has fired 22 missiles, including two across Japan, during 15 tests since February this year, drawing a sharp reaction from the US and its allies.

In 2012 Kim described the two nations as "friendly neighbours linked by the same mountain and rivers" and bilateral ties as the "common precious wealth associated with the wisdom and efforts of the leaders of the elder generations".

Beijing has been reluctant to slap sanctions harsh enough to rattle the North's political status quo over fears that its collapse could send an influx of refugees across their shared border and place the US army at China's doorstep.

But in a sign of irritation at its unpredictable neighbour, Beijing cut all its coal imports from the North earlier this year and voted in favour of broader UN sanctions imposed on Pyongyang in recent months.

China's state-run news agency Xinhua reported that Xi said he expects to work with Trump to "jointly blueprint future development of China-US ties".

Trump is slated to visit China early next month. In a tweet, Senator Marco Rubio said that the 19th Party Congress has concluded with Xi more firmly in the grip of power.

China has the world's second-largest economy after the US, its biggest trading partner.

However, relations have been strained by Beijing's territorial disputes in the South China Sea and East China Sea with Washington's allies in East Asia.