She said the strike was being called in protest against the president's privatisation plans, pro-business economic reforms and the recent deal with Washington to resume imports of US beef.
"The results showed a public sense of crisis about the unilateral way President Lee Myung-bak has so far run state affairs," she told the AFP news agency.
Calls to resign
About 30,000 lorry drivers are already on strike over soaring fuel prices in a protest that has paralysed operations at the export-dependent country's ports.
|A strike by lorry drivers has threatened to |
paralyse South Korea's economy [Reuters]
The past month has seen escalating street protests against the South Korean leader, with calls growing for him to stand down.
The protests originally focused on a deal to resume US beef imports and fears that it would expose South Korean consumers to the risk of mad cow disease, or BSE.
But as the protests have grown they have become a lightening rod for more widespread opposition to Lee's presidency.
Lee was elected to office last December in the biggest landslide ever seen in South Korean presidential elections.
But after just four months in office his popularity ratings have dived to around 20 per cent.