The official Korean Central News Agency said the conference took place "at a critical time", with attendees urged to redouble their efforts to push leader Kim Jong Un's ideological line.

The Kim family has ruled the country for more than seven decades with an iron fist wrapped in a pervasive personality cult, propagated via state media.

The North is regularly rated one of the worst countries in the world in terms of press freedom.

The conference, held on Monday and Tuesday in Pyongyang, was the first time the union has convened since Kim was declared leader in 2011.

It emphasised that journalists "should become ardent believers, staunch defenders and thorough implementers of the revolutionary idea of" Kim, KCNA said.

Last year the North declared itself an "irreversible" nuclear power, and Kim this year ordered his military to intensify preparations for a "real war".

The impoverished country has also been struggling to tackle chronic food shortages, with some reports of starvation emerging.

Wednesday's KCNA report said conference attendees were told a political and ideological campaign must be "vigorously launched" to inspire "the entire country" to implement the regime's rural development strategy.

"In North Korea, journalists are the elite warriors of the party's political propaganda," said An Chan-il, a defector-turned-researcher who runs the World Institute for North Korea Studies.

"It's an order from the regime to write articles that are much more fierce and loyal to Kim. The fact that the North feels it needs more propaganda may signify that its food situation is not getting any better."

An told AFP the convention could also suggest another nuclear test was coming, "perhaps on April 15th -- the birth anniversary of (the North's) founder Kim Il Sung".

"The regime may have wanted to prepare its reporters before the massive coverage of the test."