US President Donald Trump has said China is working with Washington to solve “the North Korea problem”, as tensions continue to mount over Pyongyang’s weapon’s program.

Mr Trump also defended his decision not to label China a currency manipulator – a major promise during his election campaign – linking the issue to North Korea in a tweet on Sunday.

The US president had previously signaled that China held the key to easing tensions over North Korea, but more recently he has suggested that the US would act unilaterally if Beijing failed to rein in its wayward neighbour.

However, he appeared more upbeat on Beijing and Washington working together to actively confront Pyongyang in a tweet on Sunday.

"Why would I call China a currency manipulator when they are working with us on the North Korean problem?” Mr Trump tweeted, a week after he said he wouldn’t declare Beijing a currency manipulator.

“We will see what happens!" he added in Sunday’s tweet.

Tensions have escalated sharply over North Korea since Mr Trump sent an aircraft carrier group into the region earlier this month.