Air China has suspended flights to North Korea, further limiting the secretive state's links with the outside world, but the company said Wednesday it was a business decision.

The suspension comes shortly after US President Donald Trump visited Beijing and pressed his counterpart Xi Jinping to do more to rein in North Korea's nuclear programme.

China sent a special envoy, Song Tao, to the North last week but his four-day trip ended with no direct statement on the crisis, after Pyongyang's series of nuclear and missile tests triggered global alarm.

Air China said in a statement to AFP that it cancelled the Beijing to Pyongyang flight route because the "operational situation is not ideal".

"Market conditions will determine the resumption of the flight route," the statement said.