A huge offshore crane is being used to salvage parts of the sunken ship
North Korea has denied sinking a South Korean warship near their disputed maritime border last month.
"As South Korea can't identify the cause of the accident, they are using the media to attribute it to us," said a statement carried by state media.
It is the first official comment by Pyongyang on the incident, in which more than 40 sailors were killed.
South Korean media has has pinned the blame on the North, but official statements have been more circumspect.
There has been speculation in the South that the naval vessel was hit by a North Korean torpedo.
South Korean officials have also previously suggested the ship could have struck an old mine left over from the 1950-1953 Korean War.
North Korea accused the South of "a foolish attempt" to link the incident to Pyongyang, said an official statement published by the Korean Central News Agency.
Fifty-eight crew survived, but 46 sailors died in the incident on 26 March.
Salvage workers found 36 bodies in the shattered hull of the Cheonan, a 1,200-tonne navy gunboat.
Two more bodies were recovered earlier, and another eight sailors remain unaccounted for.
The bow section of the vessel is due to be raised in about a week's time.
The Cheonan sank close to the sea border which marks North and South Korean territorial waters.
The North does not accept the maritime border, known as the Northern Limit Line, which was drawn unilaterally by the US-led United Nations Command at the end of the Korean War.
The sea border has been the scene of deadly clashes between the navies of the two Koreas in the past.