Riot police were out in force during the transmission to prevent further trouble.

The documentary, broadcast by Seoul-based Munhwa Broadcasting Corporation (MBC), examines claims that sect leader Lee Jae-rok could cure illness by touch.

Mr Lee heads the 65,000-strong Manmin Chungang Sungkyol sect, a Protestant denomination whose name roughly translates as All Holiness Church.

The organisation was thrown out of the Christian Council of Korea last month in a row over "heretical" claims.

Sit-down protest

Several hundred sect members invaded the television station late on Tuesday evening, cutting power supplies five minutes after the hour-long programme had started.

They said the TV station had distorted the facts and defamed the sect's image.

MBC officials estimated 50 protesters had overpowered security guards and broken into the control room where they cut the power. The picture was restored, but lost again on three further occasions.

An MBC spokesman said: "The programme was interrupted just five minutes after it began. We had to broadcast other programmes instead."

Others attacked the producer of the programme, entitled PD-Notepad, and then held a sit-in in the lobby. Another 1,500 supporters blocked a neighbouring street with a sit-down protest.

At least 600 South Korean riot police were mobilised to end the occupation.

Arrests

Six people were arrested during the incident, which is understood to have ended without injuries. Investigators are reportedly seeking to question church leaders in relation to the incident, although it is not thought that Mr Lee is wanted.