North Korean leader Kim Jong Un has said he is ready for war if provoked by "invasive" outsiders, but avoided past threats centring on the country's nuclear weapons and long-range missile ambitions.

Kim's New Year comments, broadcast by North Korea's state TV, largely stuck to the well-worn propaganda meant to glorify him and his leadership for the residents of one of the world's poorest, most closed countries.

But his words will still be pored over by analysts for hints about the country's intentions for the coming year.

There is little public information about the inner workings and policy goals of North Korea's government, which considers democratic South Korea and its ally the United States its enemies, and is pursuing a long-range missile that could carry a nuclear warhead to America's mainland.

Kim did not directly offer dialogue to Seoul and Washington, but said he was open to talks with anyone truly interested in "reconciliation and peace" on the Korean Peninsula.

He also vowed to improve North Korea's struggling economy.

Analysts say Kim probably wants a push for tangible diplomatic and economic achievements before a convention of the ruling Workers' Party in May, the party's first since 1980, when he is widely expected to announce major state polices and shake up the country's political elite to further consolidate his power.

Some had predicted that Kim would avoid overly provocative statements in his New Year's address because the county wants to improve relations with South Korea and also China, its most important economic and strategic ally.

Ties between North Korea and China have been noticeably cooler since Kim took power in 2011, but China seemed to take a step towards mending relations when it sent a senior official to a high-profile military parade in Pyongyang in October.

The rival Koreas have been showing mixed progress in reconciliation efforts after they stepped away from a military stand-off in August, which was sparked by landmine explosions Seoul blamed on Pyongyang that maimed two South Korean soldiers.

The countries ended rare high-level talks last month with no breakthrough.