North Korea is in the final stages of preparing to test-fire an intercontinental ballistic missile (ICBM), the country's leader Kim Jong-un said Sunday, as it seeks to advance its weapons of mass destruction capability.

North Korea became a powerful state with nuclear weapons last year, boosted by the success of its hydrogen bomb and nuclear warhead explosion tests, the North's leader said in his verbal New Year's message broadcast by the state-run TV station.

"We were vibrant in developing advanced weapons (last year) ...We are in the final stages of preparing to test-fire an ICBM," Kim said.

His remarks come amid growing speculation that North Korea may carry out more powerful provocations around its key anniversaries this year to boost its internal solidarity and show off its military prowess.

North Korea conducted two nuclear tests last year alone following those in 2006, 2009 and 2013. It also launched more than 20 ballistic missiles in 2016 including the intermediate-range Musudan and those launched from a submarine.

The North's leader also warned that Pyongyang will beef up its capability for pre-emptive nuclear strikes if South Korea and the United States do not suspend their annual joint military exercises.

North Korea has long denounced the military drills between Seoul and Washington as a rehearsal for northern invasion.

The North has insisted that its development of nuclear weapons is a deterrent against what it called Washington's hostile policy toward Pyongyang.

Kim's 2017 New Year message has been closely watched by outside experts to glean possible clues for Kim's stance toward the incoming US Donald Trump administration. But his message did not include any comments on Trump. (Yonhap)