(Adds coastguard, updates death toll)
By Ju-min Park and Senggyu Lim
JINDO, South Korea, April 20 (Reuters) - Distraught relatives of hundreds of missing people inside a sunken South Korean ferry clashed with police on Sunday as coastguard divers retrieved more bodies from the ship and the number of confirmed dead rose to 49.
A rescue operation has turned into a grim search through the stricken vessel to recover the remaining 253 passengers, most of them schoolchildren on an outing, who are unaccounted for after Wednesday's capsize.
Searchers retrieved 16 bodies overnight and coastguard officials said cranes would not be deployed to lift the ship off the seabed until the bodies had been recovered.
The 69-year-old captain, Lee Joon-seok, was arrested on Saturday on charges of negligence along with two other crew members, including the third mate who was steering at the time of the capsize.
Prosecutors said the mate was steering the Sewol through the waters where it listed and capsized for the first time in her career. The ship was on a 400-km (300-mile) voyage from Incheon to the southern holiday island of Jeju island.
Until Saturday night, coastguard divers had struggled to get into the passenger quarters of the ferry which sank in 27 metres (86 feet) of water in calm seas while on the well-travelled route.
Though shallow, the murky sea is subject to some of the fiercest currents around the Korean peninsula. But ropes have been fixed to guide divers into the vessel and back out.
"We are now putting in four guide lines, before there was only one, so their access will become faster," Ko Myung-suk, a coast guard official, told a news briefing in the rescue centre in the port of Jindo.
The sinking looks set to be the country's worst maritime disaster in 21 years in terms of loss of life.
South Korean officials are still characterising the operation as a "rescue" although marine experts say that it is unlikely that there are any survivors.
Up to 100 relatives gathered near a bridge linking Jindo island to the mainland and tried to march across to take their protest to the capital, Seoul.
But police formed two lines to prevent the pushing and shoving relatives reaching the bridge.
"Bring me the body," said weeping mother Bae Sun-ok as she was comforted by two policemen at the bridge.
Early reports suggest that the ferry may have turned sharply and then listed before capsizing.
It took about two hours to go over but passengers were ordered to stay put in their cabins and not go up to the deck where they might have been rescued.
Asked why that order was given instead of abandoning the ship, Lee, apparently overwhelmed by the scale of the disaster, told reporters on Saturday he feared they would have been swept out to sea in the strong, cold current.
Of the 476 passengers and crew, 339 were either pupils or teachers from a high school in Ansan, a commuter city outside Seoul.
Relatives gathered in a gymnasium in Jindo have spent four days and nights awaiting news of their loved ones.
The vice-principal of the school, who was on the ferry and survived the capsize, hanged himself outside the gymnasium.
Investigations are looking at how the cargo was stowed, the safety record of the ship operator and the actions of the crew.
Witnesses say the captain and other crew members left the sinking ship before many of the passengers and that orders to evacuate were either not given, or not heard.
Lee has not explained why he left the vessel. (Reporting by Jumin Park; Writing by David Chance; Editing by Sandra Maler and Robert Birsel)