A China-based distributed denial of service (DDOS) attack on a financial services company has halted internet services for several hours to some customers of Australian telco Optus.
The number of other companies affected has not been revealed, but are reported to include the publishers AAP, IDG and News Limited.
The company confirmed that the DDOS attack originated from China and was aimed at a multinational financial institution in Australia, but it did not name the organisation.
China-based cyber attacks have become a growing concern for Australian businesses and government departments.
In January, the Australian government revealed that the Defence Department had investigated about 200 security incidents on its own network every month in 2009 and responded to about 220 incidents at other Australian government agencies.
Optus fended off the attack by blocking the point of interconnect on its international transmission link to the US through China, according to Australian reports.