The body of late North Korean leader Kim Jong Il lay in state at a presidential mausoleum on Tuesday, as throngs of somber, weeping mourners continued to express sorrow at the longtime leader's unexpected death.

North Korean state television showed images of Mr. Kim's body – partially covered by a red blanket – lying in a glass coffin and surrounded by flowers at Pyongyang's Kumsusan Memorial Palace.

The embalmed body of North Korea's founding president, Kim Il Sung, has been on display in a glass case at the same palace since his death in 1994.

State media reported that Kim Jong Il's youngest son and apparent successor, Kim Jong Un, visited his father's body and held a “solemn ceremony” at the palace earlier Tuesday.

The official Korean Central News Agency announced early Monday that the 69-year-old Mr. Kim died of a heart attack Saturday while traveling by train on one of his “field guidance” tours. The agency attributed his death to “physical and mental overwork.”

His funeral will be held on December 28, near the end of a period of national mourning. State media reports say foreign delegations will not be allowed to attend the ceremony.

Television footage from the closed communist state has continued to show extraordinary scenes of public grief since Mr. Kim's death was announced on Monday.

Though observers fear a power struggle following Mr. Kim's death, North Korean state media have given clear indications that he will be succeeded by Kim Jong Un. Media reports have referred to him as a “great successor” and the “pillar of our people.”

Late last year, Mr. Kim promoted Kim Jong Un to the rank of four-star general, in what was seen as a bid to extend the world's only communist dynasty to a third generation.

Kim Jong Un's influence within the North Korean leadership is uncertain. Although he was appointed to several top posts last year, analysts say he has had little time to earn the trust of power brokers in the military and the ruling Korean Workers' party.