9 North Koreans defect to the South

North Korean refugees prepare to release a balloon with leaflets condemning Kim Jong Il during a rally in Paju Wednesday.The group makes the border crossing over the weekend in the Yellow Sea They travel in a boat with no engine South Korean authorities are questioning them about their motives

Seoul, South Korea (CNN) -- Nine North Koreans defected to the South by boat over the weekend, the South Korean Joint Chiefs of Staff said Wednesday.

The group made the border crossing Saturday in the Yellow Sea off the west of the Korean peninsula, according to the JCS.

The nine defectors made the journey in an engineless boat and are being questioned by South Korean authorities about their motives and their route, South Korea's Yonhap news agency reported.

The development comes four months after a group of 31 North Koreans accidentally crossed over into South Korean waters on a fishing boat. Four members of that group decided to defect to the South, despite Pyongyang's demands that they all be repatriated to the North, the South Korean Red Cross said in March.

There are currently more than 20,000 North Korean defectors in South Korea, according to the South's Unification Ministry. The number of annual defectors has risen drastically since the turn of the century and continues to climb.

Defectors who are forcefully repatriated to the North after attempting to cross over into places such as China, Mongolia or Southeast Asia are commonly sent to prison camps as a punishment. Many defectors who live in South Korea fear for the lives of their family or relatives who remain in the North.

CNN's Paula Hancocks contributed to this report.

CNN