SEOUL (THE KOREA HERALD/ASIA NEWS NETWORK) - The ferry disaster off South Korea's south coast may have been caused by an attempt to change direction too sharply.

Reports said the Coast Guard arrived at a preliminary conclusion that the Sewol ferry turned too quickly to the left, causing it to lose balance and ultimately capsize.

Based on the accounts provided by crew members, the investigators suspected that the Sewol sharply changed direction when only a gradual change was required. As the ship lost balance, its steering equipment was thought to have malfunctioned.

According to the Ministry of Oceans and Fisheries, the Sewol took a sharp turn at 8.48am, four minutes before the Coast Guard received the first report that the ship was experiencing problems.

The ministry's analysis of the ship's monitoring system also showed that the Sewol then moved about 100 metres to the south. It drifted for about 70 minutes, moving about 1,600 metres to where it later capsized.

The sudden direction change is suspected to have pushed motor vehicles and cargo aboard the ship to one side, causing the vessel to lose balance. The Sewol was carrying 180 vehicles and over 1,100 tonnes of cargo.

The accident occurred near the point where ships on the Incheon-Jeju route usually change direction.

Survivors have told media that the Sewol jolted on two occasions as it tilted at a 90-degree angle and again as it capsized. Fishermen who took part in the early rescue efforts have given supporting accounts.

The Coast Guard summoned the ship's captain for questioning to determine further details about the situation. The captain, identified as Lee, was initially questioned as a witness but his status has since been changed to that of a suspect.

The Coast Guard also said that the Sewol deviated from the route recommended by the Ministry of Oceans and Fisheries, giving substance to the speculation that the ship's captain may have been attempting to make up for lost time. The Sewol's departure from Incheon, its port of origin, was delayed due to heavy fog.

With new evidence emerging, the authorities now suspect that the loud bang that survivors reported hearing just before the ferry began sinking was made by cargo that had come loose.

Accounts from survivors had led to speculation that the Sewol may have hit a reef when it sent out an emergency signal at 8.52am on Wednesday.