There is still no official explanation for the sinking, although the government has launched a formal inquiry.
Hundreds of South and North Koreans have been reunited for the first time in six decades after being separated by the Korean War.
North Korea has marked the 60th anniversary of the truce that ended the Korean War with a massive celebration in the capital Pyongyang.
The mother of one of the children missing after the South Korea ferry disaster has accused the government of inaction, saying they are "pretending to work."
Im Seon-mi, mother of missing girl Park Hye-seon said:
"The government are just pretending to work. But it's just a show. And the media just play their game. When we request that we need to get in there (the ship), they say something has to come from here and from there.
"But that's not true. This is a 100% man-made disaster. If the government acted quicker, all the children would have been saved."
Speaking about her daughter Hye-seon she said: "I feel like she is gone, when I should be the one who is gone"
"She did not express very much but she was warm hearted."
The captain of the sunken South Korean ferry told passengers to stay put before he and members of his crew made their escape, the country's President has claimed.
Park Geun-hye told a cabinet briefing that the captain and some crew members committed "unforgivable, murderous acts" during the disaster, which has left more than 300 people dead or missing.
She said the alleged decision of the captain and crew members to escape before ensuring their passengers' safety was "legally and ethically [...] an unimaginable act".
Two first mates, one second mate and a chief engineer have been detained on allegations they failed to protect passengers, according to the Associated Press news agency.
The four crew members are also reportedly accused of abandoning the ship.
AP says prosecutors are considering whether to apply for a formal arrest warrant to allow for a longer period of investigation.
The ferry's captain and two other crew members have already been arrested on suspicion of negligence and abandoning people in need.
Four crew members of the capsized Sewol ferry have been detained over allegations they failed to protect passengers, the Associated Press reports.
BREAKING: Prosecutor: 4 crewmembers detained for allegedly failing to protect South Korean ferry passengers.
South Korea's President Park Guen-hye has attacked the actions of the captain and some of the crew aboard the capsized Sewol ferry.
NBC News' Bill Neely reports:
S Korea's president says the actions of the captain and some of the crew of the sunken ferry #Sewol are "tantamount to murder".Strong words
New video footage has emerged appearing to show the captain of the sunken South Korean ferry receiving medical treatment soon after reaching shore following the capsizing of his ship.
The pictures obtained by the Associated Press show a man that seems to be Lee Joon-seok lying on the floor of a hospital facility at Paengmok Port.
The news agency says the footage is consistent with its own reporting and was checked by regional experts against known locations and events.
The captain was one of the first people to escape the ship on Wednesday. He has been arrested on five charges including negligence of duty and abandoning people in need.
More bodies have been recovered from a sunken ferry in South Korea, taking the death toll to 64.
None of the 302 passengers reported missing on the capsized Sewol ferry have so far been found alive.
The official number of dead from the South Korea ferry disaster has reached 59, NBC News' Bill Neely reports.
The official death toll from the Korean ferry disaster is now 59. More than 240 remain missing.Divers inside the ship overnight.More out now
After four days of frustration and failure the pace of the operation has increased. More bodies being brought in, more divers - there are hundreds of them going out to the ship. They are using axes to smash their way into the passenger area and using ropes to bring the bodies out.
For the parents; for some of them it's a relief - they desperately want their children out of the water. Others say "why didn't you do this days ago when children might have been alive?"
I've been in a gym where those parents are waiting. It's really very hard for them. Every time a body is brought ashore the details are flashed up on a screen: height, hair colour, a general description and the clothes they were wearing.
These tiny details trigger very deep emotions - there are anguished cries from the floor of the gym. One woman told me, "I just want to die because my son is dead, but I have to stay alive for my daughter." Another man said that a lot of the parents have accepted that their children are dead.
This is no longer a search and rescue operation. This is a recovery operation, a national tragedy and for the parents a long and very painful wait.
A transcript of the last communications between the the stricken South Korea ferry and a vessel traffic centre shows confusion and indecision among the ship's crew.
The ship-to-shore radio exchange, which was released today, shows a crew member questioning whether an evacuation should be ordered after the ferry had already been listing for half an hour.
An official at the Jeju Vessel Traffic Services Centre had recommended evacuation just five minutes after the Sewol ferry's distress call.
"If this ferry evacuates passengers, will they be rescued right away?" the ferry Sewol asked VTS at 0924 on Wednesday, about 30 minutes after the ship began listing.
That followed several statements from the ship, beginning at 0900, that people aboard could not move.
VTS told the Sewol security boats would arrive in 10 minutes, but did not mention another ship had said 10 minutes earlier that it would rescue anyone who went overboard.