Seoul: North Korea on Sunday lashed out at South Korea for a perceived lack of respect towards Kim Jong-Il, as it reported more scenes of mass grieving in the isolated communist state for the late leader.

Saying the whole world is in mourning for "a peerlessly great man", the North for the second time in three days blasted the South over its response to Kim's sudden death on December 17.

There would be "unpredictable catastrophic consequences" for cross-border relations unless Seoul eases restrictions on condolence visits by South Koreans to Pyongyang, it said.

The South blames it’s neighbour for two deadly border incidents last year, but has taken a generally conciliatory stance since Monday's shock announcement that Kim had died of a heart attack two days earlier at age 69.

The Seoul government sent its sympathies to the North's people, scrapped a controversial plan to display Christmas lights near the border and announced that South Koreans could send pre-approved condolence messages northwards.

But the authorities, who by law must approve all contacts with Pyongyang, are allowing only two private delegations to visit the North to pay respects and are not sending an official team.

Following the South's announcement, the North said it would open its borders to all South Koreans who wish to travel to Pyongyang.

"The South Korean authorities should bear in mind that their obstructions will entail unpredictable catastrophic consequences to the north-south relations," a spokesman for the Committee for the Peaceful Reunification of Korea, a state body overseeing cross-border relations said.

The Seoul authorities' "unethical acts bereft of elementary etiquette and compatriotism has touched off unanimous outrage and wrath among Koreans and all other people of the world", the spokesman said.

Despite the tough rhetoric, analysts generally do not expect shows of military force as the new regime headed by Kim's son Jong-Un settles in.

The North's state media has been heaping praise on both the late father and the son for the past week.

(Agencies)