FROMELLES, France - The remains of the last of 250 Australian and British soldiers whose bodies were discovered in a mass grave were being reburied on Monday on the 94th anniversary of the bloody World War I battle of Fromelles.

Prince Charles and top Australian officials were to attend the ceremony, which marks the end of more than two years of painstaking exhumation and identification work by archaeologists.

The families of some of the soldiers also were expected to attend Monday's event.

An Australian amateur historian discovered the graves - which contain the largest group of Australian remains from World War I ever found - in a muddy field on the edge of a small wood in 2008, prompting an investigation by the Australian government.

The remains appear to date from a single, famously ferocious night of fighting 90 years ago. Late on July 19, 1916, Australian forces launched the battle of Fromelles, the first Australian combat operation on the Western Front.

More than 5,500 Australians were killed, wounded or went missing at Fromelles in under 24 hours, along with more than 1,500 British, cut down by German machine guns and artillery. German troops buried them afterward, Australian investigators say. The site, near a pockmarked battlefield, was covered over time.

More than 23,000 Australian soldiers' bodies were never recovered for burial from World War I, according to the Commonwealth War Graves Commission.