Hackers claiming links to international activist group Anonymous defaced dozens of websites belonging to Australian businesses and Philippine government agencies on Sunday.
A group calling itself Anonymous Indonesia posted on Twitter a list of more than 100 Australian sites it had hacked, saying the action was in response to reports of spying by Australia.
The websites, defaced with a message reading "Stop Spying on Indonesia", are mainly owned by small Australian businesses and seemed to have been chosen at random.
Sites reported to be hit include Australian Providores, Miss Pole Australia, Queensland's Mango Tree Hotel and the NSW Tenant's Union.
The list posted by Anonymous Indonesia also includes:
News of Australia's role in a US-led surveillance network could damage relations with Indonesia, Australia's nearest Asian neighbour and an important strategic ally.
Reports that the Australian embassy in Jakarta was being used for spying prompted Indonesia to summon the Australian ambassador on Friday.
China demanded an explanation from the United States after the Sydney Morning Herald newspaper reported Australian embassies across Asia were part of the US operation.