The National Assembly dealt President Roh Moo Hyun an unexpected setback today by stalling on his request to send 700 South Korean engineers and medics to help in the war against Iraq.

The request still is likely to pass, according to political observers. But the parliament's unexpected opposition was a sign of the depth of public disapproval of the U.S. action in the Middle East.

"It's a surprise. Even though there are antiwar demonstrations in the street, people thought the assembly would pass it today," said Lee Chung Hee, a political analyst at Hankuk University of Foreign Studies.

Public opinion polls have shown heavy opposition in South Korea to supporting the U.S. attack in Iraq. A few thousand people demonstrated outside the parliament today, continuing a series of small, regular protests.

But political chieftains of Roh's party and the opposition party had agreed with the president's decision to support the United States as a loyal ally. A revolt by legislators concerned by the public mood delayed the vote until after April 2, when Roh is scheduled to lay out his arguments in a speech to the National Assembly.

South Korea is a key ally of the United States in Asia, but relations have been troubled by public resentment toward U.S. troops and the Bush administration. Roh took office a month ago after a campaign critical of South Korea's unswerving support of the United States.

But after what was reported to be a difficult debate, Roh decided last week to support the Iraqi invasion with a small force of non-combatants. The vote scheduled in the parliament today had been considered a formality.

There was no immediate comment from the government's Blue House.

President Roh Moo Hyun will present a plan for sending engineers and medics to Iraq.