Hanoi - An Australian ceremony to commemorate the 50th anniversary of a Vietnam War battle has soured into a diplomatic spat after the Vietnamese government restricted access to the site at Long Tan.

Australian Prime Minister Malcolm Turnbull made an 11th hour appeal to his Vietnamese counterpart Nguyen Xuan Phuc on behalf of about 1,000 Australian veterans and their families who had travelled to Vietnam but found themselves barred by authorities, who said the ceremony might offend residents.

"I thank the prime minister of Vietnam for agreeing last night to arrangements which will, after all, enable our veterans and their families who have travelled to Vietnam, reverently to commemorate the battle as they honor all those who fought and died in those fields so many years ago," Turnbull said in an address in Canberra on Thursday.

The commemoration had long been planned in coordination with Vietnamese authorities but was canceled on Wednesday.

Australian Veterans' Affairs Minister Dan Tehan said the formal ceremony at the Long Tan site remained canceled but Nguyen had agreed to ease the restrictions so that smaller groups of veterans could visit the site.

Tehan called the cancellation "a kick in the guts".
More than 60,000 Australians served in Vietnam between 1962 and 1972 and more than 500 Australians were killed during the deeply unpopular war between the Soviet-backed Communist government of North Vietnam and South Vietnam's U.S.-backed regime. The war ended with the fall of the former Saigon in 1975.

The 1966 battle of Lang Tan, fought in a rubber plantation in South Vietnam, was Australia's costliest of conflict. Eighteen Australian soldiers were killed and 24 wounded. North Vietnamese and Viet Cong casualties numbered about 245 killed and 350 wounded.