Opposition politicians in South Korea have forced open a room inside the parliament building in the capital, Seoul, which they say was being used by the National Intelligence Service to spy on their members of parliament.

MPs from the Grand National Party forced their way into the room on Thursday and took away materials which they said proved the intelligence agency was conducting a surveillance operation against them.

The National Intelligence service says the room is an archive for the parliamentary intelligence committee and the allegations are untrue.

The BBC Seoul correspondent says it's ironic the opposition should be making such complaints, as during their decades in power, the security agency went so far as to try to assassinate the man who's now the country's leader.

But he says, the allegations -- if true -- could be embarrassing for President Kim Dae Jung, who promised to break with Korea's repressive past when he was elected.