Five-thousand demonstrators gathered in central Seoul on Friday for what have become nightly rallies protesting against President Lee Myung-bak's decision to implement a beef import agreement with the United States.

Lee Dong-hwan was among the protesters who called for the government to cancel the import accord.

"As a citizen of this country, I believe the public right of having safe food should be protected."
Earlier in the day, three main South Korean opposition parties asked the Constitutional Court to block US beef from entering the country.

The parties said the Constitutional Court should rule that the government's policy on US beef violated the people's right to health.

They also called on the court to issue an injunction against restarting imports until a verdict is issued.

South Korea has locked out American beef for most of the past four-and-a-half years over fears of mad cow disease. The government, however, agreed with the US in April to restart imports.