HANOI (AFP) — Vietnam on Friday marked 40 years since the Tet Offensive with colourful military parades of its veterans and re-enactments of the surprise wave of urban assaults that marked a turning point in the war.

Communist Party leaders and military chiefs watched as former guerrillas and regular soldiers filed past Ho Chi Minh City's Reunification Palace, formerly the presidential palace of the US-backed Saigon regime ousted in 1975.

Youths in black Viet Cong pajamas with models of AK-47 assault rifles and rocket launchers joined the parade, as did women carrying fruit baskets on shoulder poles, recalling the way arms and bombs were smuggled into the city.

"The 1968 Tet Offensive opened a new page in the Vietnam war and struck a blow to the imperialist Americans' will to continue their aggression," said Le Thanh Hai, using the rhetoric of the Communist Party he heads in the city.

"It is one of the most glorious chapters in Vietnam's history."

More than 10,000 veterans, service members and volunteers took part in the parade, which also marked the 78th anniversary next Sunday of what was called the Indochina Communist Party when it was founded on February 3, 1930.

On the podium were Vietnam's Communist Party chief Nong Duc Manh, and Nguyen Thi Binh, who signed the 1973 Paris peace accords for the southern Provisional Revolutionary Government and later became vice-president of reunified Vietnam.

The Tet Offensive started with several attacks on January 30, but was launched in earnest in the early hours of January 31, 40 years ago Thursday.

Some 70,000 communist fighters attacked targets in more than 100 towns and cities in South Vietnam, including the former US embassy and the palace.

The audacious offensive, which violated a truce marking the traditional Tet Lunar New Year, caught US and South Vietnamese forces off-guard.

Although tens of thousands of communist soldiers were killed, it proved a psychological victory by strengthening the US anti-war movement.

"The Tet Offensive was a disaster in many respects," said Vietnam expert Carl Thayer of the Australian Defence Force Academy. "The southern communist underground was exposed and decimated. No general uprising occurred.

"But the offensive had unintended consequences that were not part of communist planning. Specifically, US President Lyndon Johnson ordered to stop bombing over the North, opened negotiations in Paris and declared he would not run again."

To mark the anniversary, propaganda posters have been put up across Vietnam's largest city, kicking off the celebrations that culminated in the pomp of Friday's nationally televised parade.

For Vietnam, which remains a communist one-party state, "these ceremonies serve to demonstrate that the party has always been correct in its strategic assessments and has brilliantly executed military strategy," said Thayer.