The 50th anniversary Vietnam War commemoration at Long Tan has been cancelled by the Vietnamese Government just one day before the ceremony.
The Departments of Foreign Affairs released a statement on Wednesday afternoon saying the federal government is "deeply disappointed" as Australia has been preparing for the event with Vietnamese authorities for 18 months.
"The Government is deeply disappointed at this decision, and the manner in which it was taken, so close to the commemoration service taking place," the DFAT statement read.
"Australia's Ambassador has registered our deep concerns with the Vice Minister for Foreign Affairs. The Government is seeking urgent calls with Vietnamese counterparts at the most senior levels to register our concerns."
The Battle of Long Tan in the Vietnam War
On August 18, 1966, 108 young and -- many inexperienced -- ANZACS fought in the pouring rain and mud at the rubber plantation of Long Tan in South Vietnam during the Vietnam War, to hold off an army of more than 2000 Viet Cong and North Vietnamese soldiers.
Eighteen ANZACS died and 24 were injured while 245 men in the Viet Cong and North Vietnamese army died. It was one of the heaviest conflicts during the war and remains one of the most well known.
Vietnam Veterans Day is celebrated on August 18 every year and commemorations have been held at Long Tan since 1989.
Minister for Veterans Affairs Dan Tehan told reporters on Wednesday that Australia was only informed about the decision last night without any warning.
The Smarttraveller website has been updated, advising Australians not to travel to the site which the Australian Government understands is currently blocked (and may remain blocked on Thursday).
More than 1000 Vietnam veterans were making their way to Long Tan for the ceremony.
Tehan said the highest levels of government are making an effort to have the decision overturned before the ceremony tomorrow.
A DFAT spokesperson told The Huffington Post Australia that Foreign Minister Julie Bishop has arranged to speak to her counterpart on Wednesday, as there has been no explanation for the cancellation.