Two South Korean students are unaccounted for after their language-learning center building collapsed in an earthquake in Christchurch, New Zealand, the foreign ministry said Wednesday.

The students, a 25-year-old man and his 21-year-old sister, are feared to have been in the building when it collapsed after a 6.3-magnitude quake hit New Zealand's second-largest city on Tuesday, said Baik Joo-hyeon, a director general in charge of consular affairs.

The two had been staying at different homes under a home stay program. Officials contacted the home where the sister was staying, and the family said she had not been back since the disaster. The family whom the brother was staying with could not be reached because they evacuated their home, the official said.

In addition, five to six more Korean students could have been in the building at the time of its collapse, but details cannot be confirmed, Baik said. So far, about 100 people have been rescued from its rubble, he said.

Two South Korean consuls arrived in the devastated city to take care of the situation. South Korea also plans to dispatch 22 rescue workers as well as two government officials to the city, Baik said.

The rescue workers and the officials plan to depart later Wednesday.

South Korea's ambassador to New Zealand, Noh Kwang-il, who was in South Korea during the quake, changed his schedule and headed back to his post Wednesday, he said.

About 5,000 South Koreans are currently living in Christchurch.

News reports say a total of at least 75 people have been killed so far, and the death toll is expected to rise with hundreds still missing.

(Yonhap News)