Kwon Ri-sae, also known as Rise, a singer in the South Korean pop group Ladies' Code, has died in hospital, aged 23 years-old.

Kwon Ri-sae is the second member of South Korean pop group Ladies' Code to die, four days after the van they were travelling in crashed near Seoul.

She had been unconscious after emergency brain surgery following Wednesday's accident, a spokesperson from Polaris Entertainment said.

The singer sustained a severe head injury after the vehicle she was in skidded off the road and crashed into a protective wall early on Wednesday.

Fellow group member Koh Eun Bi died shortly after the accident, while three other members suffered injuries including a fractured jaw.

"Rise passed away today around 10.10am (9.10am Singapore time) at age 23. Her parents and officials from her agency were by her deathbed," Polaris Entertainment, Ladies' Code's agency, said in a press release.

"We are truly sorry and grief-stricken by this tragedy, particularly after what happened to Eun Bi."

Police inspector Lee Ho-dong told the Associated Press that the crash happened when band were returning to the South Korean capital after filming a TV interview in the south-eastern city of Daegu.

The van driver was treated for a minor injury before being questioned and may have been speeding on a wet road to meet a tight schedule, Mr Lee said.

"We are investigating the exact cause of the accident," he said. "But it's difficult because the highway section where the crash occurred did not have a closed-circuit television camera."

He added that a camera from inside the van had been sent to the National Forensic Service.

The group made their debut last year and recently marked their comeback with the song, Kiss Kiss.