The United States warned China on Friday that North Korea's attendance at a weekend summit on China's new Silk Road could affect the participation of other countries, casting a shadow over what is Beijing's biggest diplomatic event of 2017. Two sources with knowledge of the situation said the US embassy in Beijing had submitted a diplomatic note to China's foreign ministry, saying that inviting North Korea sent the wrong message at a time when the world was trying to pressure Pyongyang over its repeated missile and nuclear tests.

China's Foreign Ministry did not immediately respond to a request for comment outside of working hours in China. The ministry said on Tuesday that North Korea would send a delegation to the summit but gave no other details.

Asked about the invitation to North Korea to attend, Anna Richey-Allen, a spokeswoman for the US State Department's East Asia Bureau, said the United States expected China to push its neighbour to return to "serious talks" on denuclearization.

"That includes taking steps to make clear to the (North Korean leader) Kim Jong Un regime the political, economic, and diplomatic consequences of its reckless and unlawful actions."

The United States did not think it would be appropriate for North Korea to play a prominent role at the Belt and Road Forum, according to one of the sources familiar with the US concerns.

The United States will send a delegation led by White House adviser Matt Pottinger to the summit, China's Foreign Ministry said earlier on Friday.

Copyright Reuters, 2017