Swiss President Pascal Couchepin has condemned the United States-led war against Iraq as a violation of the UN charter.
The US launched military operations on Thursday, striking targets in Iraq. "We will accept no outcome but victory," said President Bush.
Couchepin, speaking during a special session of the Swiss parliament, said Switzerland would maintain its neutrality, banning US coalition military flights in Swiss airspace during the conflict.
"The Cabinet regrets that the US and its coalition partners have transgressed the UN charter... which they helped create."
He said the UN's failure to reach a united position over Iraq had set a dangerous precedent for collective security.
Couchepin added that "no one was more responsible for this war than Saddam Hussein".
Yves Christen, speaker of the House of Representatives, expressed regret that the crisis in Iraq had led to war.
"Saddam Hussein is dangerous, but he is not Adolf Hitler... and Tony Blair is not Winston Churchill," Christen said.
Meanwhile in Geneva, the head of the International Committee of the Red Cross (ICRC) appealed to all sides in the war to abide by the Geneva Conventions, and spare civilians and prisoners.
"Even in wars, people have rights that must be protected," said Jakob Kellenberger, ICRC president.
Swiss Foreign Minister Micheline Calmy-Rey said she was "shocked" by Washington's decision to go to war.
She said she had contacted the ambassadors of all the countries involved in the conflict - the United States, Iraq, Britain, Australia, the Czech Republic and Poland - and urged them to respect international humanitarian law.
Calmy-Rey added that Switzerland was ready to participate in the reconstruction of Iraq as a legitimate and democratic state.
The Swiss foreign minister said officials were still examining a request by the US to expel three Iraqi diplomats from Switzerland.
As dawn broke over the Iraqi capital on Thursday, heavy explosions were heard in Baghdad and on its southern outskirts.
Jets were reported flying overhead, while anti-aircraft batteries opened fire.
Military officials and the White House said the attack was aimed at "very senior" Iraqi leadership, following an intelligence tip off.
"I assure you, this will not be a campaign of half measures and we will accept no outcome but victory," Bush said.
He said the military operation was the "opening stages of what will be a broad and concerted campaign".
The declaration of war came just hours after an ultimatum expired for the Iraqi leader to give up power.
swissinfo, with agencies
Swiss President Pascal Couchepin has condemned the war as a violation of the UN charter.
Couchepin said that the human rights of civilians and refugees must be respected.
He also said Switzerland would maintain its neutrality, banning US coalition military flights in Swiss airspace during the conflict.
Switzerland also announced that it was ready to participate in the reconstruction of Iraq.
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