SEOUL (AFP) - North Korea on Sunday lashed out at Japan's hawkish prime minister for seeking to revise Tokyo's pacifist post-World War II constitution, calling Shinzo Abe a "militarist maniac".

In a New Year comment Mr Abe said the country's constitution - which limits its military to self-defence - could be amended by 2020, days after his visit to a controversial war shrine in Tokyo enraged Asian neighbours.

China and South Korea see the Yasukuni Shrine as a brutal reminder of Japan's war-time aggression and failure to repent for its history.

The visit also angered the North, which last month slammed the conservative Japanese leader of "reckless behaviours" that would push Japan into "self-destruction".

The North's ruling party newspaper, the Rodong Sinmun, on Sunday heaped further criticism on Mr Abe for the New Year message, warning that Tokyo's leaders should "behave themselves".

"What Abe said was dangerous outbursts which brought to light the true colors of a militarist maniac," it said in an editorial.

Accusing the prime minister of seeking to "bring back the era... when the Japanese imperialists could dominate Asia", the paper claimed that Tokyo was taking the path of "self-destruction".

"If the present ruling forces of Japan have even an iota of reasonable thinking, they should face up to the reality and behave themselves," it said.

The communist state has habitually slammed Tokyo for failing to repent for its 1910-45 occupation of the Korean peninsula and what it calls Japan's rising military ambitions.

The North's nuclear and missile programmes have raised longstanding security concerns in Japan, which last month announced it will boost its military budget, spending $240 billion between 2014 and 2019 to buy fighter jets and other military hardware.

The move drew a typically angry response from the North, which called it a "crafty and sinister attempt to justify Japan's arms build-up and reinvasion scheme".