On April 18 this year, South Korea agreed to resume imports of US beef and remove almost all quarantine restrictions imposed over fears of mad cow disease, including those on the age of butchered cattle.

The deal was also expected to pave way for the ratification of a free trade agreement between Seoul and Washington by the US Congress.

But the deal sparked immense public concern over the mad cow disease and triggered fierce protests in South Korea. Protestors said the government did not shoulder enough responsibility to protect its citizens from potentially tainted beef.

Riot policemen run and break up protesters trying to march toward the presidential Blue House in Seoul after a candle-lit vigil June 7, 2008.(Xinhua/Reuters Photo) 

In the wake of mounting protests, the South Korean government delayed the implementation of the new quarantine standards and the deal has effectively unraveled.

However, protests have shown no signs of abating. Violence flared over the past weekend when thousands of people trying to march to the presidential office clashed with riot police in downtown Seoul. Around 60 protesters and police officers were injured during the massive confrontation.