North Korea on Thursday condemned tough new sanctions imposed by the UN Security Council over its nuclear and missile programme as a violation of its sovereignty which would escalate tensions.

A foreign ministry spokesman said in a statement that North Korea "strongly censures and categorically rejects it as another excess of authority and violation of the DPRK's sovereignty by the UNSC acting under instructions of the US," the official KCNA news agency reported.

The statement said September's nuclear test, its fifth and biggest, was taken to "tackle the nuclear threat and sanctions by the US".

Noting that the Security Council had not prevented its permanent members from conducting nuclear tests and rocket launches, it said sanctions would not force North Korea to abandon its nuclear programme.

It added that sanctions would trigger "tougher countermeasures for self-defence" and would "inevitably escalate tensions", KCNA reported.

The Security Council on Wednesday unanimously imposed its toughest ever sanctions on North Korea, placing a cap on its key coal exports after the state's defiant nuclear tests.

The new sanctions resolution, which was spearheaded by the United States and came after three months of tough negotiations with fellow veto-wielding council member China, passed by a 15-0 vote.

The resolution demands that North Korea "abandon all nuclear weapons and existing nuclear programmes" and takes aim at the state's exports of coal -- its top external revenue source.