AAP

Thousands of Australians across South-East Asia attended memorial services on Wednesday in monsoonal heat and humidity to remember the fallen from conflict and wars spanning the region's 20th century history.

In Vietnam, as the 40th anniversary marking the end of Australia's involvement in the war nears, more than 500 people attended a service in the forested enclave of the Long Tan Cross site in Nui Dat province. The site was made famous by a 1966 battle between Australian forces and Communist Viet Cong.

In the decade-long Vietnam War, which polarised opinion at home, 3629 Australian service personnel died or were injured.

In Thailand in the early light of a jungle dawn, hundreds of Australian families and those of former prisoners of war attended services near Kanchanaburi's infamous Death Railway, 200km west of Bangkok.

The ceremonies included a dawn service at the Hell Fire Pass railway cutting some 60km from Kanchanaburi town, along the railway's route between Thailand and Burma.

Tens of thousands died during construction of the line between Thailand and Burma, also known as Myanmar. From the 60,000 prisoners of war who worked on the line, 12,400 perished including 2,800 Australians.

The railway's construction also claimed the lives of 100,000 Asian labourers from a workforce of 200,000. Largely Tamils, Malays and Burmese, they were forced to work on the line's construction for Japan's Imperial Army.

Later, Australian and New Zealand ambassadors and officials laid wreaths at a mid-morning memorial ceremony at the war graves cemetery in Kanchanaburi town. In Burma, up to 100 people were expected at the Commonwealth War Cemetery outside Rangoon.

In Malaysia, memorial services were held in Kuala Lumpur, Penang and at the Sandakan war cemetery in Sabah state.

In Sandakan hundreds of POWs, 1,381 Australians and 641 British prisoners, and thousands of Indonesian slave labourers and local Malays, perished while constructing a military airstrip and later during "death marches".

Services remembering Australian and New Zealand participation in Malaysia's Emergency conflict against Communist guerrillas, in which more than 80 Australian and New Zealanders perished, are also marked in June.

In Singapore, Australian and New Zealand communities gathered at the traditional dawn service at Kranji Commonwealth War Cemetery and laid wreaths, which was followed by a Gunfire Breakfast.