ATHENS, August 6, 2008 (AFP) - A Greek prosecutor on Wednesday upgraded the charges against four nightclub staff who allegedly beat an Australian tourist to death in Greece on the island of Mykonos, a justice source said.

A 25-year-old bouncer who allegedly bashed 20-year-old Australian Doujon Zammit with a baton has now been charged with voluntary homicide while three other staff members were charged as accessories, the source said.

The case is being handled by authorities on the island of Syros, the administrative centre for the Cyclades group of islands.

The four suspects had respectively faced attempted murder and complicity charges but the situation changed over the weekend when Zammit died after his life support was turned off with his father's approval.

Only the bouncer had been remanded in custody and Zammit's father Oliver had expressed frustration over the court's initial decision to release the other three suspects on bail, but the upgraded charges could now place all four in pre-trial detention after they testify.

Doujon Zammit was among six Australians caught up in an incident early last Tuesday morning at the Tropicana club on Mykonos island's Paradise beach.

The Australians were suspected of having stolen bags and wallets in the nightclubs, an accusation later dismissed by police.

Oliver Zammit donated his son's heart, kidneys, liver and lungs to four people, including a 30-year-old Greek Australian in hospital in Athens.

Hundreds of Mykonos residents gathered at the island's harbour on Saturday to denounce Zammit's killing.