South Korea's ruling party rammed the country's free trade agreement with the European Union through parliament amid an opposition boycott in a result that shifts focus to a still unratified deal with the United States.

The approval, which paves the way for the tariff-slashing accord to take effect as early as July, came in a one-sided late night vote Wednesday that saw Grand National Party lawmakers wield their majority in the National Assembly. EU lawmakers approved the deal earlier this year.

The free trade agreement brings together increasingly affluent South Korea, Asia's fourth-largest economy, with the 27-member EU, the world's largest economic bloc. Trade between the two sides totaled $92.2 billion last year, a gain of 17 percent from the year before. It is the EU's first such accord with an Asian country.

A total of 169 National Assembly members were present and 163 voted in favor of the legislation, which passed a little more than an hour before midnight. One lawmaker voted against it while five abstained. The assembly has 299 members.

"I announce that the free trade agreement between the Republic of Korea and the European Union has been ratified," National Assembly Speaker Park Hee-tae said after the vote.

The main opposition Democratic Party boycotted the session in a dispute about providing safeguards for farmers and small retailers, Yonhap news agency reported.

Members of the smaller Democratic Labor Party protested by standing near the speaker's chair and holding up signs reading "Oppose the Korea-EU FTA" after Park ended debate ahead of the vote.

Negotiations toward an agreement began four years ago soon after South Korea and the United States concluded negotiations on a free trade deal. Despite the later start, Seoul and Brussels stand to see their accord take effect first — a potential development that has worried U.S. businesses who see European rivals potentially gaining an advantage in the South Korean market.

The EU ranks as South Korea's fourth-largest trading partner behind China, the Association of Southeast Asian Nations and Japan. The U.S. is South Korea's fifth-largest trading partner.

South Korea and the EU signed their agreement in October of last year and EU lawmakers approved it by a wide margin in February. Both sides have said they want it to take effect on July 1st.

Seoul's Ministry of Foreign Affairs and Trade welcomed the passage, saying it can help South Korea better weather global economic challenges such as Japan's earthquake, political changes in the Middle East and North Africa and South Korea's strengthening currency.

"We expect the Korea-EU FTA to improve our companies' overseas trade environment," the ministry said in a statement.

EU Trade Commissioner Karel De Gucht, meanwhile, said the agreement will lead to growth and create jobs, among other benefits.

"This is a landmark agreement and a benchmark for what we want to achieve with other key trading partners," he said in a statement.

The passage comes as South Korea's free trade deal with the U.S. remains unratified in both countries. Secretary of State Hillary Rodham Clinton said last month during a visit to Seoul that the administration of President Barack Obama is determined to see the agreement passed this year.

The deal is the biggest for the U.S. since the North American Free Trade Agreement in 1994 and would bring the country economically closer to South Korea, already a key long-term security ally.

The South Korea-U.S. agreement, negotiated under the administration of President George W. Bush, stalled under Obama after his government complained the pact did not adequately address a large deficit in auto trade favoring Seoul. The two sides reached a revised deal in December that the U.S. said it felt could win congressional approval.

In Washington, the White House said Wednesday it was ready to send free trade deals with Colombia, Panama and South Korea to Congress for approval. The first step in the process, technical discussions with congressional aides, could begin as early as Thursday.

The White House had hoped for quick approval of the deal with Seoul. But Republicans threatened to block it unless the Obama administration also completed agreements with Colombia and Panama. That breakthrough came in April, after months of negotiations.