SEOUL: South Korea's spy agency warned that North Korea might conduct another nuclear test after Pyongyang detonated what it said was a miniaturised atomic device on Tuesday.

The warning came during a briefing to lawmakers by the head of the National Intelligence Service, Won Hei-Soon, Yonhap news agency reported.

The briefing raised "the possibility for another nuclear test by the North" or a ballistic missile test once the UN Security Council begins discussions on imposing new sanctions on Pyongyang, Yonhap said.

"The North may stage other provocations to distract international efforts to impose more sanctions on the North or to push China to eventually side with Pyongyang," Won was quoted as saying.

Despite the North's claim that Tuesday's test was of a "miniaturised and lighter atomic bomb", Won said his agency did not believe Pyongyang had yet succeeded in "weaponising its nuclear bombs".

Proof that the North had mastered miniaturisation techniques would be a major step towards placing a nuclear warhead on a long-range missile.

Won said the North had defied the international community and pushed ahead with the test to rally domestic support for its young leader Kim Jong-Un and strengthen its future negotiating hand.