SEOUL -- A South Korean civic delegation left for the United States Monday to demand a retrial of two U.S. soldiers acquitted of killing two girls in a road accident, and a direct apology from the president.

"We are visiting the United States to secure a direct apology from President George W. Bush," said the seven-member delegation, led by Presbyterian Church Priest Hong Keun-soo, in a statement.

"We will also demand the U.S. court-martial's verdict be nullified to have the soldiers tried again in a Korean court," it said.

Hong heads a coalition of 130 South Korean civic groups which have organized anti-U.S. protests since the 14-year-old girls were crushed to death by a 50-ton military vehicle on their way to a birthday party on June 13, AFP reported.

A U.S. military court cleared the soldiers of negligent homicide two weeks ago and South Korean activists have since then stepped up protests, burning U.S. flags and breaking into U.S. Army bases.

Delegation members would seek to meet Bush and UN Secretary General Kofi Annan during their 10-day trip, the statement said.

Bush last week offered an apology for the deaths through the U.S. Embassy in Seoul, but it has failed to soothe public anger here.

Twice on Sunday South Korean Internet users and hackers attacked the White House computer server with electronic mail bombs in protest. It was not known how many people were involved in the cyber attack.

Some 300 other protestors marched with candles near the U.S. Embassy in Seoul, and four students broke into a U.S. food supply base in Bupyeong, on the western outskirts of Seoul.

Two of the students climbed up a 30-meter (100-foot) high water tower.

Protestors are calling for the withdrawal of 37,000 U.S. troops stationed in South Korea under a mutual defense pact dating back to the 1950-1953 Korean War.

Under an accord between Washington and Seoul, U.S. troops here come under U.S. jurisdiction for crimes committed while on duty. South Korean groups have urged Washington to revise the accord.

The U.S. soldiers in question left for the United States last week.

Many Koreans are bewildered that the soldiers walked free and that no one has been held legally responsible for the deaths of the girls. Under the Korean Criminal Justice System, the soldiers would almost certainly have been jailed.