Authorities detain at least 15 people after police clash with demonstrators in the capital Seoul.

Riot police used water cannons to disperse protesters gathered in front of the National Assembly [Reuters]

South Korean authorities have detained at least 15 people after police clashed with protesters demonstrating against the country’s free-trade agreement with the US.

Riot police used water cannons on Thursday to disperse an estimated 2,000 protesters who gathered in front of the National Assembly in the capital Seoul, before a parliamentary vote to ratify the pact.

The South Korea-US Free Trade Agreement (FTA) has been approved by the government but still requires approval from Korea’s legislature.

The protesters claimed the pact would endanger their country’s agriculture industry by flooding the market with cheaper imported goods.

“This agreement is totally shameful and it betrays our country,” Kim Won-yeol, a protester, said.

“This agreement also seriously damages our citizens’ goods, so many people have gathered here to stop the FTA from being ratified at the National Assembly.”

The demonstrators said they wanted Lee Myung-bak, the country’s president, and his ruling Grand National Party to renegotiate the deal with the US.

Korea’s parliament was scheduled to vote to ratify the FTA at its general meeting on Thursday afternoon.

The pact is America’s biggest free-trade agreement since the 1994 North American Free Trade Agreement (NAFTA) with Canada and Mexico.

South Korea is the world’s 12th largest economy and US-South Korea trade amounted to $90.2bn last year.