A South Korean court has jailed the former head of a disabled care home for sexually assaulting multiple residents, in a case that shocked the nation.

The man, surnamed Kim, was handed a 15-year prison term for abusing three residents at the Saekdongwon facility in Incheon City, west of Seoul. The ruling is subject to appeal.

Police started investigating Kim after one of his victims, a woman with a severe intellectual disability, came forward in February last year.

The case has prompted the government to inspect 1,507 care facilities for disabled people across the country, where 33 cases of suspected abuse were found.

South Korean Prime Minister Kim Min-seok had described the abuse at Saekdongwon as "a grave matter that calls into question the very reason for the state's existence".

An in-depth assessment of residents commissioned by Ganghwa County found that 20 current and former female residents may have experienced sexual abuse.

Many in South Korea have asked how such a case could still occur, especially after laws were strengthened in 2011 to protect people with disabilities from sexual assault.

Some have also raised questions on how the director's actions could have gone undetected for so long.

Ganghwa County has ordered Saekdongwon to close, while Incheon City officials revoked the licence of the foundation that operated it.

However, the closure has been deferred until the remaining residents have been relocated and arrangements for independent living have been completed.

The foundation has filed an administrative lawsuit challenging the revocation of its licence.