An opposition lawmaker threw a tear gas inside the South Korea's parliament Tuesday in protest to a plenary session to ratify a controversial bill establishing a free trade agreement (FTA) with the U.S.

Rep. Kim Sun-dong of the Democratic Labor Party (DLP) threw the tear gas bomb near the Speaker's seat occupied by vice parliamentary speaker Chung Ui-hwa when the ruling Grand National Party called for a voting on the FTA bill.

No one was seriously injured though some lawmakers temporarily vacated their seats to avoid inhaling the tear gas.

National Assembly police removed Kim from the chamber and Speaker Park Hee-tae ordered the parliament to be locked down to prevent physical clashes between ruling and opposition lawmakers, who have been blocking the passage of the FTA bill.

The bill was eventually passed by a 151-7 vote. Most opposition lawmakers abstained.

The DLP had been blocking the passage of the bill unless a clause on dispute settlement favoring the U.S. is revised. It also rejected appeals by President Lee Myung-bak for passage of the bill before a revision and renegotiation of the FTA is made.

The presidential office issued a statement welcoming the passage of the bill and promising that measures will be pursued to make local farmers competitive.

The FTA increases U.S. exports to South Korea by $10 billion. Under the pact, tariffs on cars and fruits will be removed gradually in 10 years.

Previous protest against the ratification of the FTA saw a civilian protester set himself on fire. Farmers and union workers also demonstrated outside the parliament rejecting the FTA bill.