BEIJING (AFP) - Beijing's Olympic torch relay has run into trouble even before the official start, with cities along the route in China and abroad beefing up security and bracing for more problems down the road.

The relay is billed as the most ambitious of all time with the "high point" being an ascent of Mount Everest in May and several hotspots along the route, including a controversial Tibet leg in June.

Protestors defied tight security to disrupt the torch-lighting ceremony in Ancient Olympia last Monday and concern about potential trouble has dogged the week-long relay through Greece, which is not part of the relay proper.

The relay officially starts on Tuesday in Beijing when the sacred flame is scheduled to depart for Almaty. The Kazakh capital is the first stop on an odyssey through 19 countries during April that is followed by an epic three-month tour around China.

The torch arrives in Beijing on Monday following a handover ceremony in Athens the previous day when the Beijing Olympic organising committee officially take charge of the sacred flame.

Security is tight in the Chinese capital and details have yet to be released concerning the torch welcoming ceremony scheduled for Tiananmen Square on Monday.

China branded the protests a week earlier in Greece "shameful" and has put pressure on cities along the international route to ensure smooth progress while stops inside China such as Shanghai say they are stepping up security.

The torch relay is the longest ever, lasting 130 days and covering 137,000 kilometres (85,000 miles) and offers ample opportunity for demonstrations on an array of issues including Tibet, whose government in exile claims up to 140 people have died in recent anti-China unrest while Beijing puts the death toll at 20.

Pro-Tibet activists and others are planning demonstrations at various points along the way, including London on April 6, Paris on April 7 and San Francisco on April 9, the only stop in the United States.

Other potential trouble spots include New Delhi on April 17. The Chinese government has already approached India about security arrangements.

"Security has been tightened. Things are under control," said Indian Olympic Association president Suresh Kalmadi.

Police in Bangkok say they are confident of guaranteeing security on April 19.

"National intelligence agencies and police in Thailand are working hard to provide high security for the torch relay," said General Yuthasak Sasiprabha, chairman of the Olympic Committee of Thailand.

Police are stepping up security in other potential flashpoints, including Japan, where the city of Nagano will host a leg on April 26. The budget for security has been boosted to six million yen (60,000 dollars) from 4.5 million.

Tibetan residents in Japan plan to stage a rally in Nagano but have vowed not to disrupt the relay itself.

Security for the Canberra leg on April 24 will also be tight and may be beefed up further if necessary, said the chief minister for the Australian Capital Territory, Jon Stanhope.

"Canberra has the advantage of hosting the torch later in the global tour, and will be able to learn from the experience of other cities along the way," he said.

Campaign groups are also planning protests in China but officials here and in Tibet, where the torch is expected to be in mid-June, are confident there will be no security breaches, even during the ascent of Everest, scheduled for May.

"To our knowledge, some separatists from within and outside China are seeking to sabotage the Olympic torch relay within Tibet," Baema Chilain, vice chairman of the Tibetan regional government, told Chinese reporters.

"We are confident and capable of ensuring the security of the relay and taking it to the top of the peak."

On Chinese soil, Hong Kong represents one of the biggest headaches for Beijing.

Hong Kong enjoys much greater freedoms than mainland China, and political protests are a regular feature of the former British colony.

The torch will arrive there on April 30, and the relay is due to be held on May 2, according to local organisers.

Timothy Fok, president of the city's Olympic committee, earlier this year appealed for Hong Kong residents to embody the ideal of the "One World One Dream" -- Beijing's Olympic slogan.

But there are no signs that the authorities will try to prevent peaceful protests along the route.