SEOUL - Some 160 people stranded in waters off South Korea's south-western coast after their ship ran aground on Sunday (March 25) has been rescued by the Coast Guard.

The ferry was carrying 163 people - 158 passengers and five crew members - when it hit a rock as it tried to avoid a fishing boat amid dense fog near Shinan county, 400km south of Seoul.

"It seems that the ferry's front grazed the rock after it changed directions to avoid a fishing boat passing by," said an official, according to the Independent.

The Coast Guard initially said the ferry was carrying 187 passengers, but later revised the number to 158, the Associated Press (AP) reported.

Six people were being treated for mild injuries resulting from the shock of the crash, which thrust the ferry's front to mount the rock, AP reported an official as speaking on condition of anonymity.

Investigators will be questioning the ferry's captain and crew, another coast guard official from the nearby port of Mokpo was reported as saying by AP. Alcohol tests showed that none of them had been drinking before the accident, he said.

The ferry, named "Pink Dolphin", is a high-speed ferry that can carry up to 250 passengers, The Korea Herald reported.

The area is not far from where an overloaded 6,825-tonne ferry carrying 476 people capsized in April 2014. That incident killed more than 300 people, mostly schoolchildren, in one of the country's worst maritime disasters.

The Sewol sinking and botched rescue efforts dealt a crushing blow to now-ousted president Park Geun Hye.

Investigations concluded that the sinking of the Sewol was the result of numerous human factors, including an illegal redesign, an overloaded cargo bay and inexperienced crew.

Video footage of the crew abandoning the Sewol after instructing passengers to remain in their cabins had caused outrage and calls for harsh punishment.

The captain of the ferry, Lee Joon Seok, was found guilty of homicide and sentenced to life in prison.