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South Korea's ruling party forced a long-stalled free trade deal with the United States through parliament Tuesday, enraging opposition lawmakers who blasted their political rivals with tear gas.

South Korean lawmakers voted 151 to 7 in favor of ratifying the landmark trade agreement in a surprise legislative session called by the ruling Grand National Party, parliamentary officials said.

Shouts and screams filled the National Assembly as ruling party lawmakers forced their way onto the parliamentary floor. Amid the scuffling, one opposition lawmaker doused rivals with tear gas.
Security guards hustled him out of the chamber as he shouted and tried to resist. Outside the National Assembly building, opponents of the deal scuffled with police mobilized to maintain order.

The pact is America's biggest free-trade agreement since the 1994 North American Free Trade Agreement with Canada and Mexico. Two-way trade between the United States and South Korea, Asia's fourth-largest economy, totaled about $90 billion last year, according to the South Korean government.

After the deal was approved less than an hour after the tussle began, dozens of opposition lawmakers and aides -- who fought hard to prevent passage of an agreement they say favors U.S. over South Korean workers -- sat slumped around the chamber podium. One legislator leaned her head against the shoulder of another as they both stared at the floor in silence.

Such chaotic scenes are not uncommon in South Korea's parliament, where rival parties have a history of resorting to physical confrontation over highly charged issues. In 2008, opposition lawmakers used a sledgehammer to try and force their way into a barricaded committee room to stop the ruling party from introducing a debate on the U.S. trade deal.

President Lee Myung-bak's ruling party commands a majority in South Korea's single-chamber, 295-seat parliament but hadn't forced the deal through earlier, apparently out of worry over a public backlash ahead of next year's presidential and parliamentary elections.

The presidential Blue House welcomed the deal's passage, pledging in a statement to use it as a chance to boost the economy and create jobs. The main opposition Democratic Party said it would boycott all other parliamentary sessions in protest and demanded that top ruling party leaders resign.

Lawmakers have been wrangling over ratification of the free trade deal since U.S. Congress and President Barack Obama approved the deal last month after years of divisive debate in the U.S.

A key sticking point was a provision that opponents say would allow investors to take disputes falling under the agreement's jurisdiction to a U.S.-influenced international arbitration panel. The opposition calls for removal of the provision.

President Lee offered to seek re-negotiation of the provision if the opponents in parliament vote for ratification. The Democratic Party, however, rebuffed Lee's proposal, saying negotiations should take place first.

Debate over the deal has been heated, with nearly daily protests outside the National Assembly and opposition lawmakers camping out in a committee room for weeks to block the vote.

Earlier this month, South Korean police fired water cannons to disperse more than 2,000 protesters trying to break into the National Assembly during a debate.

There were concerns the demonstrations might mirror those in 2008, when South Korea's move to lift a ban on U.S. beef triggered weeks of massive street protests over worries about the meat's safety and criticism that Seoul had made too many concessions to Washington.

Economist Jung Tae-in said the trade deal would widen the gap between haves and have-nots. "South Korea will falter in the early stages of the implementation of the deal because the United States is economically more powerful," he said.

But Kim Jung-sik, an economics professor at Seoul's Yonsei University, said fears about damage to South Korea's economy are overblown. "Free trade still works to South Korea's advantage because the country is so reliant on exports."

South Korea, a major exporter of industrial goods such as automobiles and consumer electronics, has aggressively sought free trade agreements and already has several in effect, including with Chile, India, the 10-member Association of Southeast Asian Nations and the European Union.

The Ministry of Foreign Affairs and Trade said in a statement Tuesday that it will work to get the trade deal to take effect on Jan. 1, 2012.