SEOUL - SOUTH Korea's main opposition party filed a criminal lawsuit on Sunday against the country's parliament speaker and police chief over a scuffle that left about 100 party members and security guards injured.

About 150 security guards - many police officers - tried on Saturday to clear opposition lawmakers who have been staging a sit-in inside the National Assembly to thwart President Lee Myung-bak's party from ramming through scores of bills including a free trade deal with the US.

The guards - acting on Assembly Speaker Kim Hyong-o's instructions to 'keep order' - frog-marched some of the Democratic Party lawmakers and their aides, who fiercely fought back. The shoving match left some 50 people on each side injured.

On Sunday, the Democratic Party filed a criminal lawsuit with prosecutors against Assembly Speaker Kim, police chief Eo Cheong-soo and two other parliamentary officials, accusing them of abuse of their power.

'(Kim's) right to keep order ... doesn't include the rights to exercise physical force,' the party said in a statement.

Seoul prosecution official Park June-tae said prosecutors plan to review the suit on Monday to decide whether to open a criminal investigation into the case.

The ruling Grand National Party, which has 172 seats in the 299-seat legislature, has said it wants to pass some 80 bills, including the free trade deal, before the current parliamentary session ends Jan. 8.

The Democratic Party said the trade pact should not be approved until Lee's government works out measures to protect farmers, laborers and others who are expected to suffer from a surge in imports from the U.S.

Another point of dispute is a GNP-sponsored bill aimed at easing restriction on businesses and newspapers owning broadcast stations.

Critics say the bill would help large pro-government newspapers and companies establish television stations, thus giving the Lee government too much leverage with broadcasters. -- AP