Vietnam says there will be no service to commemorate the 50th anniversary of Long Tan. Portarlington's Peter Nash was among the 108 heroic Australian soldiers. Picture: Jay Town

The prime minister said on Wednesday he is deeply disappointed at the Vietnamese government’s decision and will seek a telephone call with his counterpart.

“This decision and especially its timing shows a disregard for those Australians who have in good faith travelled to Vietnam to participate in this week’s events,” he told a Long Tan dinner in Canberra on Wednesday.

PM Malcolm Turnbull attending the 50th Anniversary of Battle of Long Tan Parliamentary reception for Vietnam veterans at Parliament House, Canberra. Picture Kym SmithSource:News Corp Australia

More than 1,000 Australian veterans and their families have travelled to Vietnam to observe the anniversary of the Battle of Long Tan on Thursday at a cross marking the site where 18 Australian soldiers and hundreds of North Vietnamese and Vietcong troops died in a rubber plantation on August 18, 1966.

But after 18 months of negotiations between Vietnamese and Australian officials over the commemoration, which has drawn some Australian veterans back to the Communist country for the first time since the war, Vietnam told Australia late Tuesday the event was cancelled, Veterans’ Affairs Minister Dan Tehan said earlier Wednesday.

Mr Tehan described the move as “extraordinary” and told reporters in Canberra that he made the announcement with “bitter, bitter disappointment”.

“Our heartfelt sympathies go out to the over 1,000 veterans who have travelled to Vietnam to mark this commemoration with respect and with dignity,” Mr Tehan said.

“For us, to be given such short notice of the cancellation is — to put it in very frank terms — a kick in the guts.”

The battle was one of Australia’s bloodiest days of the Vietnam War, which ended in the deaths of 18 Australian soldiers.

Vietnam Veterans Association of Australia National President Ken Foster, with Veterans Affairs Minister Dan Tehan, says the news will be a blow to veterans who had planned to attend the service. Picture: Kym SmithSource:News Corp Australia

In the fighting, a company of 105 Australian soldiers plus three New Zealanders supported by artillery survived a rain-drenched, three-hour battle by driving off wave after wave of attacks by more than 2,000 enemy troops.

Mr Tehan said the veto reflected “deep sensitivities” within Vietnamese and was not a response to problems in the bilateral relationship.

Foreign Minister Julie Bishop said that despite the ban, an official party including the Australian and New Zealand ambassadors will lay a wreath Thursday and small groups will have access to the site on the day.

Australian deployed more than 60,000 military personnel to Vietnam between 1962 and 1973, of whom 521 were killed.

Long Tan survivor Alan Fraser of Salisbury, South Australia. More than 1000 veterans had travelled to Vietnam for the now cancelled service.Source:Supplied

Vietnam Veterans Association of Australia National President Ken Foster said the news would be a blow to veterans who had planned to attend the service — some returning for the first time.

“They go over there and, as far as I know, 99 per cent of the Australian veterans go over there are respectful to the community, all they want to do is pay respects to the place where they fought and where their friends died.

“It wasn’t to commemorate anything else, it was purely to pay respects to those are dead.

“I do have concerns for the mental welfare of not only those Vietnam veterans in Vietnam, but also those here in Australia.”

President of the Vietnam Veterans Association Terry Roe. Picture: Kim EiszeleSource:News Corp Australia