A video of South Korean worker Kim Sun-Il, held by a purported Iraqi group calling itself Jamaat al-Tawhid and Jihad, shocked and outraged South Koreans on Monday.
The capture gave South Korean anti-Iraq-war parties and groups ammunition in their campaign to reverse Seoul's decision to send a 3000-troop detachment to Iraq.
"The first demonstration was held last night in central Seoul, with civic activists, students and members of a labour party holding candlelights to appeal for the release of their compatriot," Hyun Kim, a reporter with South Korea's Yonhap News Agency, told Aljazeera.net.
"Morning reports say there were also demonstrations in other cities, like the second largest city of Busan, demanding the withdrawal of the deployment plan."
On Monday, the South Korean government rejected the captor's demands under threat of execution and decided to go ahead with plans to dispatch troops by late July.
Nevertheless, South Korean civic society mobilised in a nationwide plea made through various media including Aljazeera.
Eo Yong Sun of the Democratic Labour Party of South Korea said that Koreans in general opposed the war, oppose the deployment of Korean troops in Iraq, and are pleading with Kim's captors to let him go.
Kim Sun-Il's parents are asking
for his safe return home
"We hope the Jamaat al-Tawhid and Jihad group get our point; we are against deployment of our troops in Iraq," Yong Sun told Aljazeera.net.
South Korean academics are concerned an execution of a Korean in Iraq may sour ties between the two countries.
"What I am concerned and afraid is that the case of kidnapping Mr Kim Sun-Il will damage the arduous accomplishments and difficult future tasks of Korean and Iraqi people," said Kyu-hyung Cho, a professor at Seoul's Korea University.
"I strongly urge [the captors] to reflect the general Korean people's concern and anxiousness about this serious incident between two civil friends," he said.
Political parties also issued statements condemning the invasion of Iraq and pleading for the release of their countryman.
Aljazeera aired a videotaped appeal from two members of the Uri party to the Iraqi people and the purported group holding Kim.
"Our troops are not invaders," the videotape said. "They are there to help rebuild Iraq and promote peace and stability for all Iraqi people."
South Koreans are anxious for
any news of the captive's fate
Iraq Pabyeong Bandae Bisang Gungmin Haengdong, the Korean Network Against Dispatching Troops To Iraq, which is is an umbrella organisation of 365 Korean anti-war groups, said in a statement to Aljazeera.net: "Today the Korean people were overcome with shock at the news the Korean Kim Sun-Il has been kidnapped in Iraq.
"The Iraqi people are right to resist the US's unjust invasion, occupation, and carnage. Nevertheless, kidnapping and threatening a private citizen with death cannot be justified."
As the deadline set by the captors passed, Seoul woke to a second day of anxiety. Kim's fate remains undetermined as the government engaged in fierce 11th hour diplomacy to secure his release.
"People are shocked and grieved. You can read a sense of anxiety and grief from news reports and from street talks," said Hyun Kim.
"But they know this is something that cannot be separated from the troop dispatch issue. All pray for Kim, but their views on the troop dispatch plan are sharply divided."
Some internet polls show many South Koreans have turned away from the government's plan, she said.