Donald Trump has dismissed North Korea's claim to be developing missiles capable of striking America.

In a tweet, the US president-elect derided the claim by North Korea's Kim Jong-un that preparations were in the final stage, saying: "It won't happen."

It was not clear if Mr Trump was expressing doubts about North Korea's nuclear capabilities or was planning preventative action.

Mr Trump also berated China for failing to help rein in its ally North Korea.

"China has been taking out massive amounts of money & wealth from the U.S. in totally one-sided trade, but won't help with North Korea. Nice!" Mr Trump tweeted.

In his New Year message at the weekend, Mr Kim Jong-un said North Korea was close to testing long-range missiles capable of carrying nuclear warheads.

North Korea has conducted two nuclear tests in the past year, including its biggest one to date. This raised fears that it has made significant nuclear advances.

But it has never successfully test-fired such a missile.

UN resolutions call for an end to the country's nuclear and missile tests.