Antiwar emotions ran high across the world on Saturday with millions expressing their resolve to oppose any aggression on Iraq.

In what could be the biggest protests ever seen in the United Kingdom in modern times, 500,000 marchers took to the streets in London.

Bearing placards proclaiming 'No war on Iraq', blowing whistles and cheering, thousands set off from the embankment by the Thames River and headed towards Hyde Park.

The demonstrations came a day after UN weapons inspectors presented their updated report to the UN Security Council, deepening the schism between the five permanent members.

The protests in the UK came as Prime Minister Tony Blair said he 'respected' and understood the desire to march.

"I ask the marchers to understand this: I do not seek unpopularity as a badge of honour," he said.

In Moscow, anti-US demonstrators with placards reading 'Now Iraq -- Russia next' marched.

American flags and effigies of President Gorge W Bush were burnt in Krasnoyarsk [Siberia], Krasnodar [Black Sea region], Voronezh [Central Russia], Ekaterinburg [the Urals] and some other cities, Russian media reported.

Over one thousand marched from the foreign ministry building in Moscow to the US embassy to express their solidarity with the people of Iraq.

War opponents also planned protests near the UN in New York.

In Athens, police fired teargas shells and clashed with several protestors who smashed store windows and threw a gasoline bomb at a newspaper office.

In Pakistan, however, the protests were relatively low key; some 3,000 people, including schoolchildren, writers, lawyers marched a day after President Pervez Musharraf told his US counterpart over phone that a war with Iraq 'is not a good option'.

In Seoul, some 2,000 people chanting 'no war, no war', 'Yankees go home' rallied to protest against the looming war in Iraq and to call for a peaceful solution to the nuclear crisis in North Korea.

In Baghdad, Iraqis march in support of their leader Saddam Hussein, dancing to drums and tambourines, many armed with Kalashnikovs.

'Our swords are out of their sheaths, ready for battle', read one banner. Many hoisted giant pictures of Saddam.

In Kuala Lumpur, about 2,000 anti-war demonstrators gathered outside the American embassy.

The protestors, including Australians, Americans and Belgians besides Malaysians, carried banners and placards bearing slogans such as 'No war. Stop US aggression', 'No more blood for oil' and 'Drop Bush not bombs'.

Australia faced a weekend of protests on a scale not seen since the Vietnam War.

More than 100,000 antiwar demonstrators jammed the centre of Melbourne on Friday and tens of thousands more took to the streets of Perth, Hobart, Canberra and numerous regional centres on Saturday.

Organisers said the Sydney rally, which will be attended by numerous celebrities from stage, screen and the arts on Sunday, could be the largest seen in Australia since the early 1970s.

Hundreds also marched on the streets of Tokyo. About 300 people, including Europeans and other foreigners, joined the sit-in protest in front of the US embassy for about one-and-a-half hours.

In Nepal, over 1,500 people, including Gurkha soldiers, students and human rights activists attended a mass rally, witnesses said.

The demonstrators in Kathmandu chanted slogans like 'We need peace, not war' and 'Follow the rules of the UN'.

The youngest person to climb Mount Everest, Temba Sherpa, 17, spoke at the rally and said the world needed peace and security without a breach of fundamental human rights.

The demonstration disrupted traffic in Kathmandu for a couple of hours, the witnesses said.