The Beijing Olympic flame arrived in Vietnam's Ho Chi Minh City late on Monday from North Korea, an AFP photographer saw, on one of the final legs of its troubled worldwide journey.
The torch arrived at around 11:20 pm local time (1620 GMT) -- after a trouble-free relay in Pyongyang -- in communist Vietnam's largest city, formerly Saigon, where security was tight ahead of Tuesday's relay.
About 100 security forces were on duty at the city's international airport.
Vietnam's government has promised its northern neighbour and communist ally China that the relay will not be marred by protesters, following pro-Tibet demonstrations in cities including London, Paris and San Francisco.
Vietnamese activists have announced plans to peacefully protest against Beijing's claim over the disputed Spratly and Paracel island chains in the South China Sea, leading to several police detentions in recent days.
Street rallies are rare in Vietnam, a one-party state, but activists said they planned to protest on Tuesday in the Capital Hanoi and the southern port of Ho Chi Minh City, where the relay was set to start at 1130 GMT.