By Ellen Wulfhorst and Paul Majendie

NEW YORK/LONDON (Reuters) - More than six million protesters took to the streets around the globe on Saturday to send a passionate message to President Bush not to invade Iraq and to give peace a chance.

In a huge wave of demonstrations not seen since the Vietnam War era, anti-war marchers in more than 600 towns and cities from Canberra to Cape Town to Chicago called on Bush to back off his hawkish stance toward Iraq, which his administration accuses of hiding weapons of mass destruction that pose a global threat.

"This war is solely about oil. George Bush has never given a damn about human rights," said Mayor Ken Livingstone in London, where at least half a million people marched in the biggest peace demonstration in British history creating a major headache for Prime Minister Tony Blair, Bush's closest ally.

In New York, South African Archbishop Desmond Tutu told demonstrators outside the United Nations that the United States should allow U.N. inspectors to finish their task of searching Iraq for illicit weapons.

"The just war says you have exhausted all possible and peaceful means, and the world says, 'No, we haven't,"' the Nobel Prize laureate said.

The largest outcries against war in Europe were in countries where leaders have vocally supported Bush's position.

Bush and Blair suffered a setback Friday to their efforts to win international backing for early military action to rid Iraq of suspected weapons of mass destruction in a dramatic showdown at the United Nations.

France, Russia, China, Germany and other nations said U.N. weapons inspections should continue in statements that seemed set to slow the introduction of a resolution the United States and Britain want to authorize the use of force.

French Prime Minister Jean-Pierre Raffarin boasted of a triumph in France's efforts to brake Washington's push for war after the French foreign minister won applause for his call for at least another month of inspections.

'GIVING PEACE A CHANCE'

"France is giving peace a chance. France is giving hope to the world and all over the world people are looking to France ...," Raffarin told parliament.

But French commentators said Baghdad had probably won only a brief reprieve.

Iraqi media said the reactions to the much-anticipated inspectors' report to the United Nations showed the United States and Britain were isolated.

Iraqi Deputy Prime Minister Tareq Aziz hailed the worldwide protests.

"They show the conscience of mankind against crime and against aggression," Aziz, Iraq's most prominent Christian, told Reuters television in Italy, where he prayed for peace.

President Saddam Hussein meanwhile told an envoy of Pope John Paul the United States wanted to attack Iraq because it was a Muslim country.

Cardinal Roger Etchegaray met the Iraqi leader for 90 minutes in Baghdad and delivered a letter from the Holy See focusing on finding a peaceful solution to the Iraqi crisis.

U.N. Secretary-General Kofi Annan said the United Nations might need to pass a new resolution on Iraq and warned Baghdad not to try to take advantage of apparent differences in the Security Council.

Annan said on Abu Dhabi television he did not believe that war was inevitable, but that arms inspections could not continue indefinitely without Baghdad's cooperation.

But Defense Secretary Donald Rumsfeld said that if it came to conflict, Washington would have at least as many allies as it did during the 1991 war to drive Iraqi troops from Kuwait.

Saturday's protests kicked off in New Zealand and Australia, where tens of thousands of people poured on to the streets. The rallies then followed the dawning day to more than 600 towns and cities stretching to California.

In America, authorities first estimated the crowd in New York at 250,000 people, but police later put the number at 100,000. Nonetheless it was the largest U.S. anti-war protests that called on Bush not to invade Iraq.

Tutu said he believed the peace marches could make a difference. "People marched and demonstrated and the Berlin Wall fell. People marched and demonstrated and apartheid ended," he said. "And now people are marching and demonstrating because they are saying no to war," he said.

Smaller U.S. protests of several thousand each were held in Chicago, Philadelphia and Santa Fe, New Mexico, while in California, thousands of protesters demonstrated in Los Angeles, San Diego, San Jose and Sacramento.

In Mexico City, around 30,000 people took to the streets brandishing placards and banners emblazoned with such messages as "Bush is an assassin" and "Yankee imperialism, murderers of the world."

"Let's say no to war, because war has never brought positive proposals for people," said 1992 Nobel Peace Prize winner Rigoberta Menchu, a Guatemalan whose country's 1960-1996 civil war saw 200,000 killings.

In the United States opinion polls show a majority of Americans favor attacking Iraq but many insist on their nation getting the support of the United Nations.

A White House spokeswoman said Bush, whose administration has deployed about 150,000 troops to the Persian Gulf region, still hoped to find a peaceful solution to the Iraq problem.

In Canada about 100,000 people demonstrated in frigid Montreal and on the west coast a long, winding march of 25,000 protesters clogged the streets of Vancouver.

In Buenos Aires, thousands rallied against the war in pouring rain downtown, where retired watchsmith Hector Rico said: "We may be a long way from the action, but U.S. warmongering is putting all our lives on the line."

'AMERICANS STRESSED'

At a protest in France, one of the staunchest opponents of war, one woman said: "The Americans were stressed by September 11 and now they are going completely overboard."

The French Interior Ministry estimated at least 300,000 people turned out to protest across the country. In Berlin, some 500,000 people attended a rally, the biggest protest in Germany since the end of World War II, authorities said.

Some two million people turned out in Spain to rail against war, including nearly 1.3 million in Barcelona, making it the city's biggest protest ever, and 600,000 in Madrid, bringing the city center to a standstill.

In Rome about a million people marched through the ancient streets under a sea of rainbow peace banners.

There were rallies in as far-flung cities as Ankara, Moscow, Glasgow and Jakarta.

The only reported incidents of violence flared in the Greek capital, Athens, where demonstrators burned a car and smashed several shop and bank windows in center of the city at the start of a protest march to the U.S. embassy by up to 50,000 people. (Additional reporting from Reuters bureaux in Paris, Rome, Sofia, Moscow, Berlin, Johannesburg, London, Zagreb, Sydney, Tokyo, Islamabad, Stockholm, Helsinski, Barcelona, New York, Havana, Chicago, Tel Aviv and Damascus)